The  Deseado  Formation 
of  Patagonia 


Frederic  Brewster  Looniis,  Ph.D. 

Professor  of  Comparative  Anatomy 
Amherst  College 


EIGHTH  AMHERST  EXPEDITION 

1911 


PUBLISHED  UNDER  THE  AUSPICES  OF 

THE  TRUSTEES  OF  AMHERST  COLLEGE 

1914 


Copyright,  1014 
BY  FREDERIC  B.  LOOMIS 


THE  RUMFORD  PRESS 
CONCORD ' N • H ' 


r 


CONTENTS 

CHAPTER  PAGE 

I.     Organization  of  the  expedition — history  of  the  work  done  in  the 

Deseado  formation I 

II.     Description  of  the  Amherst  locality — age  of  the  overlying  beds — 

age  of  underlying  beds — age  of  Deseado 6 


III.  Table  of  the  animals — study  of  the  feeding  habits — character  of 

the  habitat — the  origin  of  the  elements  of  the  Deseado  fauna       19 

IV.  Systematic    arrangement — the    Litopterna,    Eoproterotherium, 

Notodiaphorus,   Deuterotherium,   Protheosodon,  Conioptero- 
therium,  Tricoelodus,  Proadianthus 28 

V.     Typotheria,     Archaeohyrax,     Plagiarthrus,     Prohegetotherium,       53 
Prosotherium,    Propachyrucos,    Phanophilus,  Archaeophylus, 
Eutrachytherus,  Argyrohyrax,  Isoproedrium 

VI.     Rhynchippidae,    Toxodontia,    Rhynchippus,    Morphippus,    Eu- 

geniops 86 

VII.     Leontinirdae,  Leontinia,  Ancylocoelus 108 

VIII.     Nesodontidae,  Proadinotherium,  Pronesodon,  Coresodon,  Inter- 

hippus,  Nesohippus 122 

IX.     Isotemnidae,   Trimerostephanus,    Pleurocoelodon,   Lophocoelus, 

Henricofilholia 129 

X.     Homalodontotheria,  Asmodeus 134 

XI.     Astrapotheria,  Parastrapotherium 142 

XII.     Pyrotheria,  Pyrotherium IS6 

XIII.  Rodents,   Cephalomys,   Scotamys,    Litodontomys,    Asteromys, 

Eosteiromys 185 

XIV.  Edentata,    Proeutatus,    Prozaedius,  Stenotatus,  Proeuphractus, 

Peltephilus,  Palaeopeltis,  Glyptatelus,  Hapalops,  Octodonto- 
therium,  Orphodon 197 

XV.  Marsupialia,  Pharsophorus,  Notogale,  Proborhyaena,  Palaeo- 
thentes,  Pilchenia,  Callomenus,  Pseuhalmarhippus,  Parabderi- 
tes : 210 

XVI.     Birds,  Physornis,  Loxornis 225 


PREFACE 

The  results  of  the  Amherst  Patagonian  Expedition 
were  divided  into  two  parts,  the  general  features,  to- 
gether with  the  narrative,  were  reported  in  a  separate 
volume  entitled,  "Hunting  Extinct  Animals  in  the  Pata- 
gonian Pampas,"  published  in  1913.  For  this  volume  has 
been  reserved  the  description  of  the  material  found  and 
such  conclusions  as  are  directly  derived  from  that  ma- 
terial. The  material  on  which  this  work  is  based  has 
been  prepared  out  and  placed  on  exhibition  at  Amherst 
College. 

The  material  here  described  forms  a  unified  body  of 
data,  which  adds  materially  to  our  knowledge  of  the  com- 
plete animals  of  the  Tertiary  period  in  Patagonia.  There 
are  beside  this  some  small  collections  which  offer  some 
isolated  new  facts,  but  the  working  up  of  these  has  been 
reserved  for  the  future  for  small  articles,  as  the  work 
may  come  to  maturity. 

The  field  has  only  been  touched  and  a  vast  amount  of 
further  work  can  be  profitably  done  on  the  horizons  im- 
mediately preceding  and  following  the  one  described  in 
this  volume,  after  which  an  interesting  study  can  be  made 
on  the  evolution  of  a  fauna  which  developed  in  a  consid- 
erable degree  of  isolation. 

F.  B.  LOOMIS. 

March  18,  1914. 


THE  DESEADO  FORMATION  OF  PATAGONIA 

CHAPTER  I 

INTRODUCTION 

THE  material  described  and  the  conclusions  drawn 
in  the  following  pages  are  the  results  of  the  Amherst  Ex- 
pedition to  Patagonia  in  1911;  an  expedition  organized 
and  sent  out  by  the  Class  of  '96  as  a  part  of  their  fifteenth 
reunion.  The  party  consisted  of  Frederic  B.  Loomis  '96, 
Phillip  L.  Turner  'n,  Waldo  Shumway  '12,  and  William 
Stein  of  St.  Joe,  Wyoming,  and  left  Amherst  July  I,  1911, 
returning  the  first  of  February  the  ensuing  year,  having 
spent  its  time  collecting  in  the  early  Tertiary  beds  of 
Patagonia,  as  exposed  in  the  Territories  of  Chubut  and 
Santa  Cruz,  the  aim  being  to  secure  from  the  earlier  periods 
a  fuller  knowledge  of  the  vertebrate  animals,  such  as  the 
Princeton  Expeditions  obtained  for  the  Patagonian  and 
Santa  Cruz  formations.  The  narrative  of  the  expedition 
has  been  told  in  "  Hun  ting  Extinct  Animals  in  the  Pata- 
gonian Pampas." 

Material  was  found  in  various  beds,  from  the  Creta- 
ceous up  to  the  Lower  Miocene;  but  the  major  part  of 
the  fossils,  and  most  of  the  facts  new  to  science  came  from 
the  work  in  the  Deseado  Formation.  The  collections 
from  the  horizon  were  so  complete  and  interesting  that 
this  report  of  the  expedition  has  assumed  the  form  of  a 
monograph  of  the  Deseado  Formation,  otherwise  known 
as  the  Pyrotherium  beds. 

The  first  work  in  this  formation  was  done  by  Carlos 
Ameghino  who  at  various  times  between  1889  and  1894 
collected  for  his  brother,  Florentine  Ameghino,  the  latter 
studying  and  describing  the  collections  of  Carlos,  whose 


2  I  I II-;  DKSEADO  FORMATION  OF  PATAGONIA 

trips  covered  the  country  from  Chuhut  down  to  the 
Straits  of  Magellan,  and  the  various  formations  from  the 
Lower  Cretaceous  to  (he  Pampean  or  Pleistocene.  Carlos 
Amcghino  and  his  brother,  Florentine),  for  years  explored 
in  Patagonia,  going  summer  after  summer  at  their  own 
expense,  and  in  the  meantime  maintaining  a  small  book 
and  stationery  store  in  La  Plata,  the  profits  of  which  gave 
the  two  brothers  a  living  and  furnished  the  funds  for  the 
continual  expeditions.  In  the  back  of  the  store  was  the 
workshop  from  which  came  the  continuous  stream  of 
knowledge  in  regard  to  these  strange  faunas.  One  of  the 
best  pieces  of  work  done  by  the  brothers  was  the  collect- 
ing and  describing  of  the  fauna  of  the  Pyrotherium  beds 
the  bulk  of  which  is  contained  in  two  papers  entitled, 
Premiere  Contribution  a  la  Connaissance  de  la  Fauna 
mammalogique  des  Couches  a  Pyrotherium,  and  Mammi- 
feres  Cretaces  de  1'Argcntine,  Deuxieme  Contribution,  etc., 
both  published  in  the  Boletin  del  Institute  Geografico  Ar- 
gentino,  tomes  15  and  18  respectively.  These  two  papers 
give  names  to  most  of  the  forms  which  we  found,  but  the 
genera  and  species  are  based  on  very  fragmentary  and  in- 
complete material.  It  has  been  a  pleasure  to  find  the  accu- 
racy with  which  these  descriptions  were  made;  and  our  part 
has  been  chiefly  to  supplement  and  increase  the  knowledge 
of  the  various  forms,  and  to  determine  from  the  more 
complete  material  the  relationships  of  these  strange  forms. 
In  some  cases  we  have  been  able  to  assemble  all  the  parts 
of  the  animals,  and  in  the  others  to  add  more  or  less  to  the 
completion  of  the  knowledge  of  the  forms.  There  is  one 
perculiarity  of  Ameghino's  descriptions,  namely  the  ab- 
sence of  data  as  to  the  localities  where  the  forms  were 
found. 

About  1900  Tournier,  in  the  interests  of  the  Paris  Mu- 
seum, made  a  series  of  expeditions  (5)  to  Patagonia,  on 
some  of  which  he  found  a  Pyrotherium,  or  as  he  has  termed 
it  Deseado,  locality  just  south  of  the  Deseado  River, 


LOCALITIES  3 

from  which  he  gathered  a  considerable  collection  which 
has  been  described  by  Albert  Gaudry  in  various  papers 
mostly  in  the  Annales  de  Paleontologie. 

These  two  collections  and  their  collaborations  represent 
all  the  work  thus  far  done  on  the  Deseado  beds  and  fauna. 
Our  collection  is  the  first  one  of  any  considerable  size  to 
be  brought  to  North  America,  and  it  seems  to  be  by  far  the 
most  complete,  the  various  animals  being  represented  by 
more  complete  skeletons  than  in  any  of  the  previous  col- 
lections. 

The  beds  were  first  designated  as  the  Pyrotherium  beds, 
and  are  always  so  referred  to  by  F.  Ameghino.  Tournier 
and  Gaudry,  feeling  the  prejudice  which  is  fairly  general 
among  Palaeontologists  against  names  based  on  any  con- 
tained animal  (which  may  or  may  not  be  present  at  other 
localities,  which  may  extend  through  more  than  one 
period,  and  whose  name  may  be  changed  as  a  result  of 
further  knowledge)  used  the  term  Deseado  formation,  as 
his  collections  came  from  the  neighborhood  of  this  river. 
This  is  a  geographical  name  and  avoids  the  chance  for 
confusion;  so  I  have  adopted  it  throughout  this  paper,  it 
being  understood  as  an  equivalent  of  the  term  Pyrotherium 
beds. 

Ameghino  never  gave  the  exact,  or  anywhere  near  the 
exact,  localities  from  which  his  Deseado  specimens  came. 
It  was  not  until  1906,  when  his  Formations  Sedimentaires* 
appeared,  that  any  localities  were  designated,  and  there 
on  a  sketch  map  he  indicates  as  Deseado  exposures,  about 
a  dozen  points,  scattered  between  the  upper  part  of  the 
Chubut  River  to  some  25  miles  south  of  the  Deseado 
River.  These  are  included  in  an  oval  area  some  500  miles 
long  by  150  miles  wide.  Ameghino  also  suggests  on  this 
occasion  that  the  Deseado  formation  originally  extended 
over  at  least  the  whole  of  this  area.  As  will  be  seen  in  the 
next  chapter,  I  believe  that  the  deposits  of  this  age 
*  Anal.  Mus.  Nac.  Buenos  Aires,  ser.  3,  t.  8,  p.  99. 


4  THE  DESEADO  FORMATION  OF  PATAGONIA 

and  character  have  always  been  local  and  isolated.  We 
sought  for  several  of  these  localities  and  failed  to  locate 
them,  especially  those  near  Mazaredo,  and  the  northern 
one  on  the  Gulf  of  St.  George.  The  point  where  we  did 
find  our  material  I  believe  was  one  of  Ameghino's  localities, 
though  the  settlers  of  that  region  had  never  heard  of  any- 
one hunting  for  fossils  there;  but  the  settlement  had  been 
practically  all  within  the  previous  six  years,  which  was 
much  later  than  the  time  when  Carlos  Ameghino  worked 
in  the  region. 

Beside  the  foregoing,  an  exposure  of  this  age  is  reported 
by  A.  A.  Romero,  just  above  the  fork  of  the  two  branches 
of  the  Rio  Negro,  w^hich  is  some  500  miles  north  of  the 
first  group  of  localities  mentioned.  Ameghino  also  refers 
to  another  locality  in  the  Province  of  Misiones  which 
would  be  1,500  miles  north  of  the  typical  localities. 

The  collections  made  by  Tournier  for  Gaudry  came 
chiefly  from  an  exposure  south  of  the  Deseado  River, 
some  15  miles  above  the  mouth  of  the  river.* 

Our  collection  came  from  the  Chico  Branch  of  the 
Chubut  River,  about  three  miles  east  of  the  river,  and 
almost  due  west  of  Puerto  Visser.  As  mentioned  above 
on  account  of  the  close  coincidence  of  the  various  species 
and  because  Ameghino  indicates  a  locality  in  the  neigh- 
borhood, I  think  that  our  locality  is  the  same  as  one  of 
his,  I  should  judge  it  the  one  from  which  he  obtained  a 
considerable  part  of  his  types.  This  is  of  importance;  for, 
if  in  Ameghino's  type  locality,  the  determination  of  the 
species,  as  the  same  as  those  of  Ameghino's,  is  much  more 
certain. 

In  the  accompanying  map  I  have  indicated  the  locali- 
ties given  by  Ameghino,  those  of  Tournier,  and  our  own. 

*Bul.  Soc.  Geol.  France,  ser.  4,  t.  3,  1903,  p.  468. 


Fig.  i.  Map  of  Patagonia  showing  localities  of  Deseado  beds. 


CHAPTER  II 

AGE  OF  THE  DESEADO  FORMATION 

THE  locality  worked  by  the  Amherst  party  is  situated 
about  three  miles  east  of  the  Chico  River,  just  across  the 
line  of  the  homestead  of  D.  J.  Venter  as  plotted  on  the 
Piano  de  la  Gobernation  del  Chubut,  1910,  by  A.  Lefrancois. 
This  would  be  45°  10'  S.,  and  67°  32'  W.  (or  as  on  the  map 
9°  15'  W.  of  the  meridian  of  Buenos  Aires).  The  exposure 
is  on  all  sides  of  an  elongated  hill  about  a  sixth  of  a  mile 
long,  averaging  200  feet  wide,  and  constricted  in  the  middle 
to  a  narrow  neck.  Figure  2  shows  a  section  of  the  hill, 
made  along  the  north  side,  and  indicates  the  varied  charac- 
ter of  the  stratified  deposits. 

The  material  varies  from  brown  sandy  clay  shales,  to 
yellow  sandy  clay  with  concretions,  and  is  capped  with  a 
varying  layer  of  greenish  sand,  which,  in  some  places,  is 
coarse  and  irregular,  in  others  fine  and  uniform,  and  in 
still  other  places  is  mixed  with  considerable  quantities  of 
volcanic  ash.  In  it  are  many  mud  balls  and  also  bits  of 
bone  which  have  been  worn  round,  others  but  slightly 
worn,  and  finally  bones  and  skeletons  which  apparently 
have  been  buried  where  they  fell.  This  green  sand  is  mostly 
covered  with  a  layer  of  two  feet  of  hard  sandstone  of  the 
same  composition  as  the  rest  of  the  bed,  but  cemented 
into  a  dense  layer.  Above  the  green  sand  is  a  layer  of 
fine  grey  sand,  prettily  crossbedded,  and  of  varying  thick- 
ness, but  without  fossils.  Remains  of  vertebrate  animals 
occurred  in  the  brown  clay,  the  yellow  clay  and  the  green 
sand,  and  in  all  the  cases  fossils  were  of  unusual  abundance 
so  that  in  this  limited  locality  we  collected  over  300  speci- 
mens. 

Above  the  Deseado  (layers  2  to  5)  lies  the  Patagonian 
in  its  typical  development,  filled  with  Ostrea  ingens, 


8  THE  DESEADO  FORMATION  OF  PATAGONIA 

Turritellas,  Brachiopoda,  sharks'  teeth,  etc.  It  is  separated 
from  the  Deseado  by  a  marked  unconformity,  one  of 
the  finest  examples  of  unconformity  I  have  ever  seen. 
Evidently  the  upper  surface  of  the  Deseado  was  fairly  new 
at  the  time  of  the  transgression,  or  k  is  much  disturbed  by 
the  transgression,  the  upper  layers  in  places  being  broken  up 
into  sort  of  blocks  and  the  crevices  filled  with  Patagonian 
sands  with  the  contained  shells;  just  as  I  saw  the  beds 
on  the  seashore  being  disturbed  by  the  waves  of  today. 
Then  too  in  the  basal  foot  of  the  Patagonian  I  found 
material  which  without  question  came  from  the  underly- 
inp  Deseado  beds,  various  fragments  of  mammal  bones 
bored  by  seashells,  and  with  the  Patagonian  barnacles 
on  them,  but  these  were  never  more  than  a  few  inches  up 
in  the  Patagonian.  The  contact  was  not  horizontal,  but 
in  the  middle  of  the  hill  dipped  down  so  that  it  came  there 
onto  the  yellow  beds  of  clays,  and  it  was  at  this  point  only 
where  we  found  bones  had  been  washed  out  by  the  Pata- 
gonian sea. 

In  the  section  the  Deseado  consists  of  layers  2  to  5, 
the  white  sandy  clay  below  belonging  to  the  St.  George 
series  and  being  Cretaceous.  The  contact  below  was 
also  an  unconformity,  clearly  marked  for  the  white  sandy 
clays  were  all  horizontally  bedded,  while  the  Deseado  is 
crossbedded  in  every  direction,  and  has  a  distinct  color. 
These  white  sandy  clays  of  the  St.  George  series  are  simi- 
lar to  the  same  beds  as  shown  in  sections  A  and  B  (figures 
3  and  4),  and  extend  in  all  directions  for  miles.  Going 
down  toward  the  Chico  River  one  passes  into  the  green 
shales  that  make  up  the  upper  part  of  the  Salamanca  and 
had  similar  invertebrate  fossils.  About  ten  miles  to  the 
north  was  another  bed  of  fossil  trees  similar  to  the  one  to 
be  described  on  the  Puerto  Visser  side  of  the  pampa. 

The  character  of  the  material  making  up  the  Deseado 
deposit,  its  variations  in  size  and  material,  the  presence 
of  worn  pebbles  and  bits  of  bone,  show  these  layers  to  be  a 


A  RIVER  DEPOSIT  9 

water  deposit.  The  absence  of  any  marine  fossil  in  a  bed 
otherwise  rich  in  fossils  indicated  that  it  was  a  fresh  water 
formation.  The  crossbedding,  the  irregularity  of  the  de- 
posits and  the  mud  balls,  prove  that  it  was  the  work  of  a 
river.  As  there  are  no  aquatic  forms  in  the  fauna  I  further 
conclude  that  it  was  the  deposit  of  a  temporary  or  inter- 
mittent stream,  such  as  occur  in  arid  and  semiarid  coun- 
tries. The  layer  could  hardly  be  interpreted  as  a  part  of 
a  flood  plain;  for  it  is  very  limited  in  extent,  there  being 
bluffs  on  three  sides  of  our  exposure,  but  in  them  no  trace 
of  the  Deseado  was  found,  nor  was  I  able  to  pick  up  the 
formation  again  across  the  Chico  River.  Then  the  bed- 
ding is  very  irregular,  much  more  so  than  is  typical  of  flood 
plain  deposits.  The  conclusion  I  reach  then  is  that  this 
Deseado  pocket  represents  the  bottom  of  an  ancient 
stream,  which  flowed  over  a  land  surface  made  up  of  the 
white  sandy  clays  of  the  St.  George  age. 

The  age  then  of  the  Deseado  beds  must  be  older  than 
the  Patagonian,  and  younger  than  the  white  sandy  clays 
of  the  St.  George. 

As  to  the  age  of  the  Patagonian  two  very  divergent 
positions  have  been  taken,  which  may  be  best  indicated 
by  the  diagram  on  page  10. 

Without  going  into  the  history  of  the  various  positions 
which  different  authors  have  taken,  and  which  will  be 
found  given  in  detail  in  Wilckens'  paper,  or  in  less  detail 
in  Ortmann's,  we  will  consider  the  positions  of  the  most 
recent  students  of  the  question.  Ameghino  postulates  a 
marine  and  a  continental  series  of  deposits  being  laid  down 
more  or  less  simultaneously.  In  the  marine  series  below 
the  Deseado,  which  is  grouped  as  Guarantic,  he  places 
the  Luisa,  the  Roca  and  the  Salamanca,  followed  by  a 
hiatus,  then  the  Sehuen,  which  in  turn  is  followed  by  an- 
other hiatus  and  the  end  of  the  Cretaceous  is  reached. 
The  Patagonian  is  his  Eocene.  Parallel  to  the  marine 
series  is  the  terrestrial,  where  the  Casamayor  (=  Notos- 


10 


THE  DESEADO  FORMATION  OF  PATAr.ONIA 


AMEGHINO,  1906* 

WlLCKENS,  1906! 

ORTMANN,  190  it 

Lower  Miocene 

terrestrial 

marine 

Patagonian 
(transgression) 

Patagonian 

Oligocene 

Deseado 

(regression) 

. 

g 

Santa  Cruz 
Notohippus 
Astrapotheri- 
culus 
Colpodon 

Patagonian 

Casamayor 
(regression) 

Upper 
Cretaceous 

Deseado 
Astraponotus 
Casamayor 

Sehuen 

Salamanca 
Roca 
Luisa 

St.  George 
(transgression) 

*  Formations  Sedementaires,   p.  498,  Anal.  Mus.  Nac.  Buenos  Aires,  ser. 
3,  t.  8. 

f  Neues  Jarhbuch  fur  Mineralogie.  bd.  21,  p.  193. 
|  Princeton  Expeditions  Reports,  vol.  4,  p.  303. 

tylops)  is  contemporaneous  with  the  Salamanca,  the 
Deseado  with  the  Sehuen,  and  the  Colpodon,  the  Noto- 
hippus and  Astrapothericulus  with  the  Patagonian,  thus 
making  the  Deseado  of  Cretaceous  age.  After  a  very 
detailed  study  of  a  large  series  of  Patagonian  fossils,  Ort- 
mann  concludes  that  the  Patagonian  is  of  Lower  Miocene 
age.  This  is  the  most  detailed  study  which  has  been  made. 
Wilckens  coincides  with  this  view,  though  feeling  that  the 
Patagonian  may  have  extended  down  a  trifle  into  the  last 
of  the  Oligocene.  This  latter  author  finds  a  long  gap  be- 
tween the  Upper  Cretaceous  and  the  Patagonian,  a  period 
when  Patagonia  was  above  water.  It  was  during  this 


AMEGHINO'S  SECTION  II 

interval  that  the  Casamayor,  the  Deseado  and  possibly 
other  beds  were  deposited  on  the  continent.  I  have  gone 
over  Ortmann's  argument,  and  studied  a  large  collection 
of  Patagonian  fossils,  both  vertebrate  and  invertebrate, 
of  my  own ;  and  while  there  are  some  places  where  we  would 
like  further  data,  I  can  come  to  no  other  conclusion  but 
that  these  Patagonian  beds  are  Lower  Miocene,  the  exact 
relationship  with  beds  in  North  America  and  Europe,  being 
as  yet  not  definitely  settled,  nor  will  this  be  possible  until 
a  study  of  the  migrations  of  the  elements  of  the  Patagonian 
fauna  has  been  made. 

As  to  the  beds  underlying  the  Patagonian,  I  am  sure  that 
a  considerable  study  of  the  marine  series  is  still  requisite 
to  determine  the  relationships  of  the  beds  in  different  parts 
of  Argentine,  and  their  relative  positions  as  compared  with 
beds  in  other  countries.  Ameghino  appended  to  his  paper 
on  the  Formations  Sedementaires  a  section  of  the  strata 
exposed  on  the  coast  of  Patagonia  from  Rio  Negro  to  Cape 
Virgenes,  on  which  from  above  Punta  Atlas  south  to  below 
Pico  Salamanca,  the  Casamayor  (  =  Notostylops)  beds 
fill  the  interval  from  the  Salamanca  formation  up  to  the 
Patagonian.  On  the  strength  of  this  map  I  followed  these 
beds  the  whole  distance  looking  for  vertebrate  fossils  of 
Casamayor  age.  Nowhere  did  we  find  a  Casamayor  fossil. 
Instead  at  several  points  we  did  find  marine  fossils.  I 
can  not  but  feel  that  these  beds  are  plotted  as  Casamayor, 
because  of  their  resemblence  in  color  and  general  texture 
to  the  beefs  carrying  the  Notostylops  fauna  at  Casamayor. 

Of  several  sections  of  these  beds  I  pick  out  two  as  typical, 
and  also  because  they  are  near  the  locality  which  we  worked 
for  the  Deseado  fauna.  On  the  map  they  are  indicated 
as  A  and  B.  The  former  passes  through  a  bed  of  green 
sands  which  is,  I  think,  the  locality  indicated  as  his  north- 
ern locality  for  the  Pyrotherium  fauna. 

From  Punta  Atlas  to  Pico  Salamanca,  Ameghino  plots 
at  or  just  below  sea  level  a  bed  known  as  the  Salamanca, 


A 


Fig.  3-  Section  at  A  on  map  page  5,  showing  strata  from  sea  level  up  to  the  Patagonian. 


Ib  IfJ  ? 

' 


^^^/^^.^:% 

^^^£4*^^' 

'//'l'///^'''//.'/'''-'-''  ///////,/-\ 

y  •. '////  w  hi  \  €  S  a  hd  u  C  CcMj  / 


alf  J 


', ''•'*•''' Viv.v'  Ve llovv, T?ed,  G hiy:'1  ;•'••;?: ;.v 


SiaUS^^ 


fc. m *  ~    ~ ^r=±r!z,^ vg€il  Ohales^  L-imes+0nfS^2 


>  >    '    ' 


Fig.  4.  Section  B  on  map,  page  5,  showing  strata  from  sea  level  up  to  the  Patagonian. 


14  THE  DESEADO  FORMATION  OF  PATAGONIA 

being  typically  developed  opposite  Pico  Salamanca. 
In  this  in  the  neighborhood  of  Pico  Salamanca  we  found 
the  fauna  typical  of  this  horizon. 

Ostrea  rostigera  v.  Ih. 
Ostrea  riongrensis  v.  Ih. 
Ostrea  ameghinoi  v.  Ih. 
Oilamys  salamanca  v.  Ih. 
Rostellaria  striatissima  v.  Ih. 
Rostellaria  sp. 
Cytherea  calcedonica  H. 
Discinia  sp. 
Diplodon  sp. 

This  Salamanca  formation  is  considered  by  \Yilckens  as 
the  equivalent  of  the  Roca  as  exposed  on  the  Rio  Negro, 
and  to  the  Luisa  as  exposed  on  the  Rio  Coyle.  All  agree 
that  the  Salamanca  is  Upper  Cretaceous  and  a  period  when 
Patagonia  was  covered  by  the  ocea'n. 

In  section  B  we  found  the  above  fauna  in  layer  I  which 
is  just  above  sea  level  here.  In  layer  2  we  found  casts  of 
delicate  marine  shells  (30  to  40  in  number),  representing 
four  or  five  species  and  as  yet  undescribed.  They  seem  to 
represent  a  deeper  water  facies  of  the  Salamanca.  In  fact 
all  the  shales  represented  by  layers  I  to  5  evidently  belong 
to  the  Salamanca.  Layer  5  was  distinguished  by  having 
in  it  at  a  point  some  200  yards  north  of  the  section  line  a 
quantity  of  turtle  shell  fragments. 

Layer  7,  consisting  of  coarser  sandstones,  was  at  the 
point  of  the  section,  simply  filled  with  a  vast  quantity  of 
fossil  wood,  most  of  it  agatized,  though  some  was  carbon- 
ized, and  representing  some  eight  species,  mostly  pines  and 
palms,  the  latter  much  scarcer.  The  tree  trunks,  hundreds 
in  number,  lay  scattered  in  all  directions;  but  all  were  lying 
horizontal,  and  there  was  no  indication  of  stumps  in  place; 
so  I  consider  that  the  wood  was  driftwood.  It  is  common 
in  the  series  of  beds  of  this  general  horizon  along  the  Gulf 
of  St.  George.  In  the  other  layers  up  to  the  Patagonian 


THE  SALAMANCA  FORMATION  15 

we  found  no  fossils.  The  contact  with  the  Patagonian 
was  unconformahle,  in  some  places  being  50  feet  higher 
than  in  others  near  by. 

In  section  A  the  typical  Salamanca  is  below  sea  level, 
and  the  lower  parts  of  the  section  are  made  up  of  the  white 
sandy  clay  shales,  so  typical  all  along  the  Gulf  of  St.  George. 
In  the  midst  of  these  clays  at  the  level  indicated  as  2  oc- 
curred a  layer  of  concretions.  On  breaking  these  we  found 
two  specimens  of  Nautilus  valencienni  H.,  clear  evidence 
that  they  were  of  marine  origin.  Layer  5  was  filled  with 
hundreds  of  the  very  characteristic  oyster,  described  as 
Ostrea  (Gryphaea)  pyrotheriorum.  Though  in  earlier 
papers  suggesting  that  O.  pyrotheriorum  represented  a 
horizon  of  marine  sediments  corresponding  in  age  to  the 
Deseado  (  =  Pyrotherium)  formation,  in  his  Formations 
Sedimentaires,  Ameghino  places  this  fossil  in  the  Sala- 
manca fauna,  though  it  here  occurs  at  least  275  feet  above 
the  typical  Salamanca  fauna.  I  believe  the  layer  should 
be  distinguished.  It  is  later  than  the  typical  Salamanca, 
though  belonging  to  the  same  transgression  of  the  sea  over 
Patagonia.  In  layer  7  we  found  still  another  marine  fauna 
consisting  of 

Ostrea  guarantica  H. 

Venericardia  sp. 

Corbula  sp. 

Aporrhais. 

Patomides. 

Oxyrhinca. 

Milobates. 

Fragments  of  the  limbs  of  a  crab  in  abundance. 

This  seems  to  be  the  same  fauna  as  that  described  by 
Ameghino  as  the  Sehuen  developed  on  the  RioSeheun. 

In  layer  8  we  found  large  quantities  of  gypsum,  occur- 
ring mostly  in  balls  of  radiate  structure.  Layer  n  was  a 
coarse  green  sand,  and  in  it  we  found  some  fragments  of 
some  sort  of  a  bone.  I  think  this  layer  is  what  Ameghino 


16  THE  DESEADO  FORMATION  OF  PATAGONIA 

designated  as  a  Deseado  exposure;  and  it  has  the  same 
general  appearance  and  color  which  is  found  in  the  green 
sands  of  the  Deseado  pocket  on  the  Rio  Chico.  However 
it  is  conformable  interbedded  with  the  underlying  and  over- 
lying marine  beds  and  I  consider  it  a  part  of  the  marine 
series.  Above  it  come  more  white  sandy  clays  that  are 
characteristic  of  the  most  of  the  section. 

Wilckens  takes  all  of  this  series,  from  the  base  of  the 
Salamanca,  up  to  the  unconformity  below  the  Patagonian, 
and  makes  of  it  his  St.  George  Period,  a  transgression 
epoch,  lasting  to  the  end  of  the  Upper  Cretaceous.  I  be- 
lieve it  is  all  marine,  and  is  all  a  part  of  the  Upper  Creta- 
ceous transgression  of  the  sea  over  Patagonia.  However 
the  Salamanca  is  a  clear  cut  deposit  and  I  feel  it  should 
be  retained  as  a  distinct  horizon.  The  overlying  light 
colored  (white,  grey,  brown,  yellow,  or  green)  sandy  clay 
shales  represent  a  deeper  water  and  later  facies,  which  is 
characteristically  developed  on  the  Gulf  of  St.  George, 
and  may  well  be  distinguished  as  the  St.  George  epoch  or 
series,  but  I  should  use  the  term  only  in  this  more  limited 
way.  It  is  the  same  series  which  Ameghino  has  plotted  as 
the  Notostylops  beds  on  his  section  of  the  coast  of  Patago- 
nia. This  last  it  certainly  is  not. 

The  unconformity  between  these  white  (or  light)  sandy 
clays  and  the  Patagonian  represents  a  regression  period, 
during  which  Patagonia  was  not  only  above  water,  but 
extended  an  unknown  distance  further  to  the  East. 

It  was  during  this  interval  of  time  between  the  Upper 
Cretaceous  and  the  Lower  Miocene  (Patagonian)  that  the 
limited  and  local  land  deposits  known  as  Casamayor 
(  =  Notostylops),  the  Astraponotus,  and  the  Deseado  (  = 
Pyrotherium)  and  probably  other  beds  were  laid  down. 
In  each  case  the  age  must  be  determined  for  the  individual 
bed  by  its  contents  mostly;  for  as  far  as  I  know  none  of 
them  overlap  anywhere. 


DINOSAUR  QUESTION  17 

In  regard  to  the  discussion  as  to  whether  Dinosaurs 
were  contemporaneous  in  South  America  with  the  fauna 
of  the  Deseado,  I  can  only  say,  we  found  no  trace  of  a  din- 
osaur or  any  other  Cretaceous  animal  in  the  Deseado  beds 
which  we  worked.  As  the  Cretaceous  beds  lie  as  high  as 
the  Deseado  and  are  also  practically  horizontally  striated, 
dinosaur  remains  might  be  found  on  the  same  level.  I 
think  the  assigning  of  any  such  material  to  these  beds  was 
due  to  failing  to  recognize  the  unconformity  under  the 
Deseado  beds.  As  to  the  Notostylops  fauna  and  dinosaurs 
being  contemporaneous,  I  only  worked  the  Notostylops 
beds  at  Mazaredo,  but  there  I  found  nothing  to  indicate 
the  contemporaneousness  of  these  two  groups.  As  I  have 
shown  above,  Ameghino's  idea  of  the  extent  of  the  Noto- 
stylops or  Casamayor  beds  was  mostly  at  fault,  and  very 
much  of  that  which  he  has  designated  as  of  Notostylops 
age  is  Upper  Cretaceous.  It  is  in  these  Upper  Cretaceous 
beds  that  dinosaurs  do  occur  and  this  seems  to  me  to  be  the 
basis  of  the  confusion. 

This  Upper  Cretaceous  series  is  a  field  where  consider- 
able work  may  profitably  be  done,  in  straightening  out 
the  relationships  of  the  various  layers  to  each  other,  their 
extent,  and  their  relationship  to  the  Salamanca  and  other 
Upper  Cretaceous  formations  in  other  parts  of  Argentine. 

As  to  the  age  of  the  Deseado  deposit  which  we  worked. 
It  is  under  the  Patagonian,  and  therefore  must  be  as  old  as 
the  Oligocene.  On  the  other  hand  it  must  be  as  young 
as  the  Eocene,  lying  as  it  does  above  the  Upper  Cretaceous. 
Of  the  three  general  faunas  described  it  is  clearly  more  ad- 
vanced than  either  the  Casamayor,  or  the  Astraponotus; 
so  should  be  put  as  the  youngest  of  these  three.  The 
Colpodon,  the  Astrapothericulus  and  the  Notohippus, 
faunas  are  said  to  be  inters tratified  with  the  Patagonian 
and  therefore  of  the  same  age.  The  amount  of  advance- 
ment from  the  Casamayor  to  the  Deseado  is  considerable 
and  the  relationships  of  the  Deseado  are  fairly  close  with 


1 8  THE  DESFADO  FORMATION  OF  PATAGONIA 

the  various  genera  of  the  Santa  Cruz;  so  that  I  should  put 
the  Deseado  as  far  up  as  possible  toward  the  Santa  Cruz. 
The  Santa  Cruz  is  above  the  Patagonian,  and  I  think  that 
the  Deseado  should  be  put  just  before  the  Patagonian; 
that  is  in  the  Oligocene,  but  just  what  part  of  the  Oligo- 
cene  can  only  be  determined  when  the  other  faunas  have 
been  further  studied. 


CHAPTER    III 

THE   DESEADO  FAUNA 

THE  exposure  of  the  Deseado,  which  the  Amherst  party 
worked,  yielded  293  specimens,  each  presumably  repre- 
senting an  individual.  (There  were  besides  these  a  few 
that  were  indeterminate  and  are  not  therefore  included.) 
The  consideration  of  the  fauna  as  a  whole  suggests  certain 
ideas  as  to  the  country  in  which  the  animals  lived,  and 
also  certain  comparisons  with  the  fauna  of  the  preceding 
and  later  faunas. 

The  first  striking  feature  is  the  presence  of  so  many 
excessively  large  animals,  as  Asmodeus,  Parastrapotherium, 
and  Pyrotherium,  in  each  case  forms  larger  than  a  rhinoce- 
ros. Further  than  that  they  are  in  each  case  the  largest 
members  of  their  family,  even  larger  than  the  representa- 
tives in  the  later  Santa  Cruz.  This  would  indicate  a  period 
in  which  living  conditions  were  at  a  high  grade,  sug- 
gesting both  abundance  of  food  and  a  moderate  climate. 

The  following  table  will  give  a  good  idea  as  to  the  range 
of  species,  and  their  relative  abundance  in  the  fauna,  also 
a  suggestion  as  to  the  class  of  food  they  used ;  and  from  that 
an  idea  as  to  what  sort  of  country  they  occupied : 

PER    NUM-  SPECIES  FOOD  COUNTRY 

CENT  BER 

3  Hegetotherium  shumwayi 
7     Prosotherium  garzoni 

17     Prosotherium  triangulidens 
I      Eutrachytherus  grandis 

4  Eutrachytherus  spegazzinius    i^JSpJJ  }    Plains 

1  Isoproedrium  solitarium 

2  Phanophilus  dorsatus 
4  Argyrohyrax  proavus 
I  Plagiarthrus  clivus 

14%     40    TYPOTHERIA 


20 


THE  DESEADO  FORMATION  OF  PATAGONIA 


PER 

SPECIES                          FOOD                       COUNTRY 

CENT 

BEE 

I 

i 

Protheosodon  coniferus                Grass                         Plains 

15 

Notodiaphorus  crassus 

6% 

16 

LlTOPTERNA 

19 

Rhynchippus  equinus                   Grass                         Plains 

7% 

19 

RHYNCHIPPIDAE 

44 

Leontinia  gaudryi                          Browse                      Brush  plains 

15% 

44 

LEONTINIDAE 

2 

Proadinotherium  leptognathus  Grass  or  Browse      Plains 

2 

Coresodon  scalpridens 

i% 

4 

NESODONTIDAE 

7 

Asmodeus  osborni                         Browse                         ? 

2% 

7 

HOMOLADONTIDAE 

6 

Parastrapotherium  holmbergi      Browse                          ? 

2% 

6 

ASTRAPOTHERIDAE 

ii 

Pyrotherium  sorondoi                  Browse                         ? 

4% 

ii 

PYROTHERIA 

55 

Cephalomys  arcidens 

22 

Cephalomys  plexus 

19 

Cephalomys  prorsus                      Hard  vegetation      Open  country 

3 

Asteromys  prospicuus 

I 

Scotamys  antiquus 

I 

Eosteiromys  medianus 

I 

Litodontomys  chubutensis 

35% 

1  02 

RODENTS 

2 

3 

2 
I 

5 
8%     23 

i 

i 
5 

2 

3%     10 

3%     ii 

100%  293 


Proeutatus  lageniformis 
Prozaedius  planus 
Prozaedius  depressus 
Proeuphractus  setiger 
Peltephilus  unclulatus 
Palaeopeltis  inornatus 
Indeterminate 
EDENTATA 

Plichenia  lucina 
Epanorthus  chubutensis 
Callimenus  praecursor 
Pharsophorus  tenax 
Pharsophorus  mitis 
MARSUPILAIA 

BIRDS 


Insects  and  leaves  Open  country 


Insects  and  flesh 


Open  country 


THE  EDENTATES  21 

In  our  collection,  all  from  one  point,  there  are  thirty- 
nine  different  species.  Beside  these  Ameghino  has  de- 
scribed a  considerable  number  of  species,  some  of  which  in 
time  will  probably  turn  up  at  our  locality;  but  others  and 
I  think  the  majority  will  be  found  to  be  representative  of 
other  localities  which  he  worked.  It  is  to  be  expected  that 
a  difference  of  locality  will  make  a  little  difference  in  the 
fauna.  Further  I  expect  that  no  two  localities  represent 
exactly  the  same  period  of  time,  though  they  may  do  so 
approximately;  but  some  of  these  local  deposits  must  have 
been  begun  earlier,  and  others  probably  lasted  to  a  later 
period.  Thirty-nine  species  of  mammals  and  land  birds 
is  a  fairly  varied  fauna  for  one  spot;  and  the  time  element 
involved  in  laying  down  the  50  feet  which  separated  the 
bottom  from  the  top  of  the  Deseado  deposit  is  not  probably 
very  long;  for  the  material  of  which  the  deposit  is  com- 
posed is  of  a  character  which  would  have  been  laid  down 
fairly  rapidly. 

Of  this  fauna  only  8  per  cent  belongs  to  the  edentates; 
and  if  any  element  were  disproportionately  represented  it 
would  be  this  one,  for  the  armadilloes  have  in  addition  to 
the  skeleton  the  hundreds  of  tiny  plates  of  the  carapace, 
and  several  of  the  forms  are  represented  by  one  or  two 
plates  only.  When  compared  with  the  condition  in  the 
Santa  Cruz  this  8  per  cent  is  strikingly  small,  for  in  that 
later  bed,  fully  50  per  cent  of  the  finds  represent  edentates. 
Are  the  Edentata  just  originating?  Or,  was  the  country 
less  favorable  to  their  habitation?  The  edentates  which 
we  did  find  are  only  slightly  less  advanced  in  their  develop- 
ment than  those  of  the  Santa  Cruz.  Also,  though  in- 
frequent, all  of  the  families  of  the  Santa  Cruz  are  repre- 
sented. It  would  seem  therefore  that  the  origin  of  the 
edentates  was  much  earlier  than  the  Deseado;  and  this 
relative  paucity  of  edentates  is  also  characteristic  of  the 
Casamayor  and  Astraponotus  beds;  but  they  are  there, 
and  in  considerable  variety,  though  small  numbers.  It 


22  THE  DESEADO  FORMATION  OF  PATAGONIA 

would  seem  then  that  the  country  for  some  reason  was  less 
adapted  to  edentates,  and  that  in  some  other  part  of 
South  America  they  were  flourishing  and  evolving. 

In  the  Deseado  the  rodents  appear  for  the  first  time  in 
South  America.  They  are  all  Hystricomorpha  and  in  a 
relatively  primitive  stage  of  development,  but  they  are 
typically  developed  already.  Did  they  migrate  in  from 
some  other  locality,  or  were  they  evolved  on  the  spot? 
Ameghino  believed  that  they  were  developed  from  some 
such  form  as  Promysops  or  Propolymastodon  of  the  Casa- 
mayor,  and  that  these  forms  were  ancestral  to  rodents  all 
over  the  world.  If  my  interpretation  of  the  age  of  these 
beds  is  anywhere  near  correct,  this  last  at  least  is  impos- 
sible, for  in  North  America  and  Europe  typical  rodents 
are  present  in  the  Eocene.  Then  as  to  even  the  hystri- 
comorphs  being  developed  in  Patagonia,  I  am  very  skep- 
tical, for  the  material  offered  in  evidence  of  this  is  very 
insufficient,  especially  in  the  region  of  the  incisors;  and 
may  be  interpreted  in  other  more  probable  ways.  I  am 
confident  that  either  just  before  the  beginning  of  the  Des- 
eado, or  at  the  beginning,  the  rodents  of  these  beds  mi- 
grated, either  from  some  other  continent,  or  at  least  from 
some  other  section  of  South  America  into  this  Patagonian 
region. 

Some  idea  of  the  type  of  country  and  the  climate  of  the 
Deseado  period  in  Patagonia  may  be  obtained  by  ana- 
lyzing the  fauna  as  to  the  character  of  its  teeth  as  indicative 
of  the  food;  and  by  studying  the  feet  as  indicative  of  the 
ground  on  which  they  were  used. 

The  Typotheria  with  their  chisel-like  front  teeth,  lack 
of  canines,  and  their  permanently  growing  grinders  evi- 
dently ate  a  hard  type  of  vegetation.  Deep  and  permanently 
growing  molars  are  characteristic  of  the  eaters  of  grass, 
a  form  of  vegetation  which  is  especially  hard  on  the  grinding 
teeth,  on  account  of  the  silica  in  the  stems  and  leaves. 
This  however  would  scarcely  necessitate  the  development 


THE  TOXODONTS  23 

of  permanently  growing  incisors.  They  are  typical  of 
gnawing  animals,  eaters  of  bark,  twigs,  and  possibly  also 
leaves,  the  wood  and  bark  being  also  a  hard  type  of  vegeta- 
tion to  grind.  In  the  case  of  these  forms  I  believe  they  were 
feeders  on  grass  and  bark.  Their  feet  are  developed  either 
for  running  or  hopping  and  would  suggest  hard  ground 
for  their  habitat. 

The  Litopterna  are  typically  plains  animals,  paralleling 
in  their  development  the  horses.  The  cropping  teeth  and 
the  grinding  molars  become  progressively  longer.  The 
limbs  are  progressively  elongated,  the  animals  walking 
more  and  more  on  the  tips  of  the  toes.  With  this,  the 
metapodials  especially  and  the  other  limb  bones  to  a  less 
degree,  are  progressively  lengthened.  At  the  same  time 
the  side  toes  are  progressively  reduced.  The  teeth  indi- 
cate grass  eating;  the  limbs  life  on  the  plains. 

The  Rhynchippidae,  while  not  as  advanced  as  the  Litop- 
terna, show  cropping  front  teeth,  and  the  molars  develop- 
ing in  depth.  The  locomotion  is  semidigitigrade,  the  feet 
small,  and  the  number  of  toes  reduced  to  three.  They  too 
must  be  interpreted  as  grazing  or  grazing  and  browsing 
animals,  living  on  hard  ground. 

The  Leontinidae  are  heavier  forms,  but  with  much  the 
same  features  as  Rynchippidae,  though  less  specialized. 
On  account  of  the  broad  upper  molars  and  the  less  special- 
ization of  the  dentition,  I  should  feel  that  these  forms  were 
browsers  and  lived  among  bushes,  but  the  feet  were  three 
toed  and  semidigitigrade  and  they  seem  to  have  walked 
on  hard  ground. 

The  Nesodontidae  belong  to  the  same  type  of  adaptation 
as  the  foregoing  family,  but  have  the  grinding  teeth  more 
complicated,  indicative  of  a  more  advanced  adaptation  to 
hard  vegetation.  The  feet  were  also  adapted  to  hard 
ground. 

The  Homalodontotheria,  the  Astrapotheria,  and  the 
Pyrotheria  were  all  very  large  animals,  known  mostly  by 


24  THE  DESEADO  FORMATION  OF  PATAGONIA 

their  dentition,  which  is  adapted  to  browse.  Whether  they 
lived  on  soft  or  hard  ground  is  not  known,  as  the  feet  are 
not  known  in  any  case  but  the  Homalodontotheridae,  where 
they  are  five  toed  and  adapted  to  soft  ground.  Such  large 
animals  were  probably  inhabitants  of  some  river  bank. 

The  rodents  do  not  contribute  much  in  the  determina- 
tion as  to  the  type  of  the  country,  for  they  could  have  lived 
in  the  open  or  in  the  wooded  country,  but  their  relative 
abundance  is  rather  typical  of  open  country. 

The  birds  are  all  running  birds,  and  indicative  of  the 
country  having  been  an  open  one. 

Of  our  fauna  1 1  per  cent  were  flesh  or  insect  eating,  and 
for  the  purpose  of  determining  the  type  of  country  may  best 
be  omitted.  The  rodents  could  have  been  either  forest  or 
open  country  forms.  Of  the  remaining  54  per  cent,  the 
typotheres,  the  litopternas,  the  Rhynchippidae,  the  Leon- 
tinidae,  the  nesodonts  and  the  birds  (46  per  cent)  were 
distinctly  adapted  to  live  on  hard  ground;  the  other  8  per 
cent  being  evidently  suited  to  living  near  a  river.  All  54 
per  cent  ate  either  grass  or  browse.  The  litopternas  are 
grass  eaters;  the  typotheres  were  specialized  to  eat  grass 
or  bark;  nesodonts,  Leontiniidae,  and  Rhynchippidae  are 
grass  and  browse  eaters.  Even  the  Pyrotherium  has  a  pair 
of  gnawing  tushes.  The  picture  arising  from  these  con- 
siderations is  a  bush  covered  prairie,  a  country  not  unlike 
the  upland  bush  pampas  of  Patagonia  today. 

There  is  not  an  aquatic  form  (fish  or  turtle)  in  the  whole 
list,  so  it  is  evident  that  the  stream  which  deposited  these 
Deseado  beds  was  not  abundantly  inhabited.  To  me  it 
looks  like  so  many  of  the  streams  in  an  arid  country,  dry 
through  a  considerable  part  of  the  year,  and  so  uninhabited. 
In  the  whole  list  I  see  nothing  to  indicate  forests  or  swamps. 
The  arid  bush  covered  plain  alone  seems  to  suit  the  re- 
quirements. 

As  I  see  this  fauna  it  is  composed  of  several  distinct 
elements,  representing  different  invasions  and  an  ele- 


VARIOUS  INVASIONS  25 

ment  which  arose  in  situ.  The  reasons  for  the  affinities 
expressed  in  the  different  groups  will  be  found  in  the  intro- 
ductory paragraphs  of  the  systematic  discussion  of  each 
group. 

The  Notungulata,  including  the  Typotheria,  the  Toxo- 
dontia,  the  Litopterna,  the  Homalodontotheria,  and  the 
Astrapotheria  are  a  group  with  apparently  a  common  an- 
cestry. In  Patagonia  they  have  specialized  into  the  various 
subdivisions  as  we  find  them  in  the  Deseado.  This  group 
was  in  Patagonia  as  early  or  earlier  than  the  Casamayor. 
Their  relationships  appear  to  me  to  be  with  the  Hyracoidea 
which  are  generally  credited  with  originating  in  Africa. 

The  Pyrotheria  are  related  to  the  early  elephants  which 
also  arose  in  Africa,  but  it  seems  to  me  that  this  form 
came  to  Patagonia  at  least  at  a  later  period,  making  its 
first  appearance  in  the  upper  part  of  the  Astraponotus 
period.  Ultimately  the  elephants  and  Hyracoidea  had  a 
common  origin  in  Africa. 

The  Rodentia  are  all  hystricomorphs  and  appear  in 
South  America  for  the  first  time  in  the  Deseado.  They 
also  occur  in  the  Oligocene  of  Europe  and  the  Fayum  of 
north  Africa.  They  never  reached  North  America  so  must 
have  come  to  South  America  by  some  southern  route. 

The  Edentata  are  an  element  of  the  Casamayor  fauna 
and  as  there  is  no  evidence  of  their  originating  anywhere 
else  it  would  seem  that  they  were  indigenous  to  South 
America,  where  they  later  flourished  and  developed  the 
greatest  variety  and  profusion  of  numbers. 

The  group  of  marsupials  is  an  element  the  origin  of  which 
presents  a  most  difficult  problem.  Some  belong  to  the 
oppossum  series  which  could  well  have  been  developed 
from  some  remnant  of  the  Mesozoic  marsupial  fauna  that 
had  a  world  wide  distribution;  but  the  presence  of  dipro- 
todonts,  which  are  characteristic  of  Australia,  and  of  the 
Borhyaenidae  which  are  closely  related  to  the  Thylacinidae 
of  Australia,  suggests  a  migration  from  that  continent  as 


26  THK  DESEADO  FORMATION  OF  PATAGONIA 

late  as  Tertiary  times;  but  to  my  mind  this  involves  a 
connection  which  is  most  too  difficult  to  postulate.  There 
is  no  evidence  that  they  came  to  South  America  in  com- 
pany with  other  faunas,  for  they  have  not  been  found 
associated  with  any  other  fauna  outside  of  Southern  Pata- 
gonia. The  explanation  of  the  affinities  of  the  Patagonian 
marsupials  with  the  Australian  marsupials  is  a  problem 
which  is  not  yet  in  position  to  be  settled. 

The  birds  probably  came  from  Africa  with  the  invasion 
of  the  ancestors  of  the  Notungulates. 

The  idea  of  an  invasion  from  Africa  in  Upper  Cretaceous 
times,  and  possibly  another  at  a  later  time  is  correlated 
with  the  other  evidence  of  a  land  bridge  between  these  two 
continents,  as  deduced  by  students  of  other  groups. 

Eigenmann,  working  on  the  freshwater  fishes,* 
Lydekker,  studying  the  hystricomorphs,f 
Von  Ihering,  studying  the  freshwater  mussels,  J 
Ortmann,  studying  the  freshwater  crabs, § 

not  to  mention  several  others  studying  mullocks,  insects, 
plants,  etc.,  have  all  postulated  a  land  connection  from 
Brazil  to  northern  Africa  during  Cretaceous  time  to  ex- 
plain the  distribution  of  their  various  groups.  The  diver- 
gence is  in  the  time  when  this  land  bridge  sank,  some  be- 
lieving it  to  have  lasted  into  Tertiary  times,  most  feeling 
that  it  sank  in  Upper  Cretaceous  times.  Another  body 
of  evidence  is  presented  to  show  that  a  land  bridge  con- 
nected the  West  Indies  with  the  Mediterranean  regions.!! 
There  was  presumably  but  one  such  transatlantic  connec- 
tion. Its  position  further  to  the  south  would  seem  to  me  to 
explain  the  distributional  facts  found  in  the  West  Indies, 
but  the  striking  resemblances  between  the  faunas  of  Africa 

*  Princeton  Expeditions  to  Patagonia,  vol.  3,  p.  310,  1905-  n. 

t  History  of  Mammals,  p.  127,  1896. 

J  Archhelenis  and  Archinotis,  p.  125-145,  1907. 

§  Proc.  Amer.  Philos.  Soc.  Philadelphia,  vol.  41,  p.  350,  1902. 

||  See  Scharff,  Distribution  and  Origin  of  Life  in  America,  Ch.  11,  1912. 


SOUTH  AMERICAN— AFRICAN  BRIDGE  27 

and  South  America  require  a  connection  from  the  South 
Upper  American  Continent  and  Africa. 

It  was  along  this  land  bridge  which  the  ancestors  of  the 
Notungulata  traveled,  and  when  in  South  America,  due  to 
their  isolation,  developed  all  the  peculiarities  of  the  group. 
This  must  have  been  not  later  than  the  latter  part  of  the 
Cretaceous. 

Either  this  bridge  remained  until  into  the  early  Ter- 
tiary; so  the  Pyrotheria  and  Hystricomorpha  made  their 
migration  later,  or  these  two  groups  did  not  reach  the 
isolated  Patagonian  section  until  later  than  the  first  inva- 
sion. I  am  inclined  to  believe  in  the  migration  being  at  a 
later  period.  This  bridge  does  not  explain  the  presence  of 
the  edentates,  for  which  there  is  every  reason  to  believe 
that  they  developed  in  situ.  The  Marsupial  invasion  must 
have  been  from  some  other  direction,  or  their  presence  in 
Africa  has  not  yet  been  discovered. 


CHAPTER  IV 

UNGULATA 

The  systematic  arrangement  of  the  South  American 
ungulates  is  of  such  a  nature  that  scarcely  two  students  of 
these  forms  have  agreed.  I  feel  that  the  Pyrotheridae  are 
proboscideans  as  did  Ameghino,  but  there  my  agreement 
ends.  The  other  varied  groups  I  believe  have  a  common 
ancestry,  their  great  divergencies  being  due  to  adaptations 
to  the  greatly  varied  characters  of  the  country  they  occu- 
pied. In  spite  of  the  great  variation  they  have  certain 
features  in  common  so  that  I  agree  with  those  who  have 
developed  the  term  Notungulata  to  include  them  all. 

From  what  source  they  originally  came  is  not  clear,  but 
it  seems  to  me  that  these  notungulates  have  more  in  com- 
mon with  what  we  know  of  the  African  fauna  of  the  Fayum 
than  with  any  other  fauna;  so  that  my  feeling  would  be 
that  these  two  faunas  had  a  common  ancestry  at  least,  and 
possibly  the  South  American  ungulates  are  derived  from 
the  African.  The  lophiodont  upper  dentition,  the  bicres- 
centric  lower  molars  with  a  "pillar"  in  the  posterior  crescent, 
the  development  of  the  tympanic  bulla  with  the  extension 
of  the  inflated  cavity  up  into  the  squamosal  bone,  the 
development  of  the  post-tympanic  portion  of  the  squa- 
mosum,  and  the  general  arrangement  of  the  basi-cranial 
foramena  indicate  in  my  mind  that  these  notungulates 
have  all  risen  from  the  same  stock,  and  that  that  stock 
had  much  in  common  with  the  hyracoids. 

I  should  therefore  arrange  the  various  groups  as  follows.* 

*  The  following  references  discuss  in  detail  the  arrangement  of  these  forms. 
Ameghino,  1906,  Formations  Sedimentaires,  Anal.  Museo  Nac.  de  Buenos 
Aires,  ser.  3,  t.  8,  p.  287-498:  Roth,  Los  Ungulados  Sudamericanos,  Anal. 
Mus.  La  Plata,  t.  5,  1903,  p.  1-36:  Scott,  Princeton  Patagonian  Expeditions, 
vol.  6,  p.  287-299,  1912:  Gregory,  Bui.  Amer.  Mus.  Nat.  Hist.,  vol.  27,  p. 
273-285,  1910. 


SYSTEMATIC  ARRANGEMENT  29 

NOTUNGULATA 

Order  I.  Upper  molars  composed  of  an  external  longi- 
tudinal crest  and  two  transverse  crests,  the  posterior  the 
less  developed ;  lower  molars  composed  of  two  joining  cres- 
cents with  a  "pillar"  in  the  posterior  crescent;  structure 
of  the  feet  and  limbs  varying. 

Suborder  i.  Litopterna:  teeth  brachydont  to  hypsodont; 
lower  molars  with  the  anterior  and  posterior  cres- 
cents subequal;  squamoso-periotic  region  not  in- 
flated; limbs  elongated;  pes  unguligrade;  digits  3-3 
or  i-i. 

Suborder  2.  Typotheria:  teeth  hypsodont  lower  molars 
with  the  anterior  crescent  shorter  than  the  poste- 
rior; squamoso-periotic  region  inflated;  limbs 
elongated  in  varying  degrees;  pes  plantigrade  to 
semi-plantigrade;  digits  5-4  or  4-4. 

Suborder  3.  Toxodontia:  teeth  brachydont  to  hypso- 
dont; lower  molars  with  the  anterior  crescent  shorter 
than  the  posterior;  squamoso-periotic  region  in- 
flated; limbs  short;  pes  semidigiti grade  to  digiti- 
grade;  digits  3-3. 

Suborder  4.  Homolodontotheria :  teeth  brachydont; 
lower  molars  similar  to  those  of  Toxodontia;  limbs 
moderately  elongate;  pes  semidigitigrade ;  digits 
with  large  curved  claws,  5-5. 

Suborder  5.  Astrapotheria :  teeth  brachydont  to  mod- 
erately hypsodont;  canines  enlarged  into  tushes; 
molars  similar  to  those  of  Toxodontia;  limbs  greatly 
elongated ;  feet  unknown. 

PROBOSCIDEA 

Order  II.     (see  page  68) 

Suborder  i.     Pyrotheria:  incisors  developed  into  tushes; 

molars    bilophodont;    limbs    short,    especially    the 

lower  element;  feet  digitigrade. 


30  THE  DESEADO  FORMATION  OF  PATAGONIA 

LITOPTERNA 

This  order  of  South  American  ungulates  is  less  abun- 
dantly represented  in  the  Deseado  formation  than  in  the 
Santa  Cruz,  but  most  of  the  genera  of  this  latter  formation 
have  representatives  in  the  Deseado  so  that  they  seem  to 
have  diverged  still  earlier. 

By  Scott  the  order  is  divided  into  two  families,  the 
Proterotheriidae  and  the  Macrauchenidae,  the  less  known 
Adiantidac  being  placed  under  the  latter  family  until 
better  known.  1  feel  that  I  should  prefer  to  retain  the 
Adiantidac  for  the  present,  until  they  can  be  shown  to  be 
subordinate  to  another  family,  so  that  in  this  paper  the 
three  families  are  retained.  The  striking  features  of  the 
two  larger  families  may  be  best  brought  out  by  a  compari- 
son of  their  chief  features  as  follows. 

Proterotheriidae  Macrauchenidae 


Upper  inc.  2  and  lower  inc.  3  enlarged  Incisors,  canine,  and  premolar  I 

and  tush-like,  growing  from  per-  simple,  compressed,  subequal  in 

sistent  pulps.  size,  and  rooted. 

Nasals  normal  Nasals  shortened  indicating  a  pro- 

boscis. 

\'c<  k  short.  Neck  long. 

Feet  with  median  digit  enlarged,  lat-  Feet  with  all  three  digits  subequal  in 

eral  digits  reduced.  size. 

Proterotheriidae  Ameghino 

In  the  Deseado,  this  family  is  scantily  represented  as 
compared  with  the  rich  fauna,  both  as  to  species  and  num- 
bers of  individuals  in  the  Santa  On/,  but  of  the  four  chief 
genera  of  the  Santa  Cruz,  three  have  been  found,  though 
the  remains  are  very  fragmentary.  They  are  the  genera 
Eoprototherium,  belonging  to  the  Prototherium  series, 
D  ciiler  other  ium  belonging  to  the  Thaotherium  series,  and 
Notodiaphorus  representing  the  Diadiaphoms  series. 


EOPROTEROTHERIUM . 


The  following  table  will  give  what  is  known  in  comparing 
the  two  series. 


Proterotherium 


PERIOD 
Santa  Cruz 


Eoproterotherium 

Deseado 

Licaphrium 

Santa  Cruz 

Diadiaphorus 

Santa  Cruz 

Notodiaphorus 

Deseado 

Thaotherium 

Santa  Cruz 

UPPER  MOLARS  NASALS  PES 

metaconule  present  normal     tridactyl 

protoconule  and  protocone  separate 

metaconule  present 

protoconule  and  protocone  separate 

metaconule  present  normal     tridactyl 

metaconule  present  short        tridactyl 

protoconule  and  protocone  fused 


Deuterotherium         Deseado 


metaconule  lacking 

protoconule  and  protocone  separate 

metaconule  lacking 

protoconule  and  protocone  separate 


tridactyl 
normal    monodactyl 


Eoproterotherium  Ameghino 

Eoproterotherium  Amegh.,  1904,  Anal.  Mus.  Nac.  B.  A.,  ser.  3,  t.  3,  p.  441. 

The  genus  is  founded  on  single  teeth  of  the  upper  molar 
series,  which,  except  for  size,  are 
very  like  those  of  Proterotherium. 
Limbs,  etc.,  are  unknown,  so  that 
this  genus  is  simply  a  carrying  back 
of  the  Proterotherium  line  into 
the  Deseado.  We  found  no  teeth  of 
this  form,  but  one  species  has  been 
described,  E.  inaequifacies,  of  which 

Ii  /*  |   •        ,        c  after  Ameghino. 

reproduce   Ameghino  s    figure   com- 
pared   with    Proterotherium,  which   shows    this  species  to 
have  the  metaconule  better  developed. 


Notodiaphorus  gen.  nov. 

The  basis  of  this  genus  is  particularly  a  hind  limb  found 
associated  which  is  much  less  developed  than  the  Santa 
Cruz  genus  Diadiaphorus  to  which  it  is  most  nearly  related. 
These  two  genera  are  unique  in  having  the  ectal  facet  on 


32  THE  DESEADO  FORMATION  OF  PATAGONIA 

the  astragulus  developed  in  two  planes  so  that  it  appears 
as  a  deep  notch.  In  the  case  of  the  new  genus  the  toes 
are  almost  equal  in  size,  giving  us  a  stage  in  the  develop- 
ment of  this  three-toed  form  which  is  much  more  primitive 
than  the  \vell-known  Santa  Cruz  genus. 

Notodiaphorus  crassus  sp.  nov. 

The  specimen  selected  as  type  is  number  3287  of  the 
Amherst  Collection,  consisting  of  a  complete  pes,  tarsus, 
lower  end  of  the  tibia,  and  the  femur, 
from  the  Deseado  on  the  Chico  del 
Chubut  River,  west  of  Puerto  Visser. 
Beside  this,  there  are  seven  other  speci- 
mens, mostly  parts  of  hind  limbs,  but 
others  having  also  the  lower  end  of  the 
humerus,  the  radius  and  ulna,  metacar- 
pals,  and  some  phalanges.  The  species 
is  distinguished  by  its  large  size,  being 
larger  than  the  species  of  the  Santa 
Cruz,  and,  at  the  same  time,  the  three 
Fig.  6.  Distal  end  of  right  toes  of  both  the  pes  and  the  manus  are 

humerus — 1/2  natural  size.  t  i    • 

subequal  in  size. 

The  distal  end  of  the  humerus  associated  indirectly 
with  this  species  is  moderately  heavy,  with  fair-sized  epi- 
condyles,  and  no  entepicondylar  foramen.  The  supra tro- 
chlear  fossa  is  moderately  deep,  the  anconeal  very  deep, 
the  two  being  connected  by  a  small  foramen,  as  is  typical 
for  this  family.  The  trochlearis,  slightly  oblique  to  the 
long  axis  of  the  shaft,  has  a  simple  pulley-like  articular 
end  without  ridges  of  division,  the  internal  border  being 
narrower  and  higher  than  the  external. 

MEASUREMENTS,  SPECIMEN  3201 

Humerus,  greatest  diameter  of  the  distal  end  58  mm- 

width  of  trochlea  on  the  anterior  side  37  mm. 

width  of  trochlea  on  the  posterior  side  28  mm. 


NOTODIAPHORUS  CRASSUS 


33 


Fig.  7.  Right  radius  and  ulna,  distal 
end  of  ulna  from  specimen  No.  3275 — 
1/2  natural  size. 
3 


Fig.   8    Left      femur    posterior    side — 1/2 
natural  size 


34  THE  DESEADO  FORMATION  OF  PATAGONIA 

The  radius  and  ulna  were  from  another  specimen  which, 
however,  was  associated  with  a  typical  astragulus.  The 
two  bones  are  long,  slender,  strongly  curved,  and  in  con- 
tact with  each  other  throughout  their  entire  length,  so 
that  there  could  have  been  no  rotary  movement  of  the  fore- 
arm. The  radius  is  a  slender  bone  with  the  proximal 
articular  facet  relatively  small,  the  facet  being  slightly 
concave,  of  ovoid  outline  and  with  the  transverse  diameter 
the  greater.  There  is  but  a  tiny  band-like  facet  for  the 
ulna  situated  on  the  posterior  side  near  the  inner  margin. 
Distally,  the  radius  widens  into  a  heavy  end  with  a  rugose 
area  on  the  outer  side  for  contact  with  the  ulna,  and  with 
two  distal  facets,  a  larger  for  the  scaphoid,  and  a  smaller 
for  the  lunar,  the  two  being  separated  by  a  low  ridge. 

The  ulna  is  heavier  above,  with  a  strong  backwardly 
directed  olecranon  process.  The  sigmoid  notch  makes 
almost  a  semicircle^  the  articular  surface  being  broad  and 
extending  well  onto  either  side  of  the  bone.  The  facets 
for  the  radius  are  tiny.  The  distal  end  of  this  bone  is 
wanting. 

MEASUREMENTS,  SPECIMEN  No.  3275 
Radius,  length  251   mm. 

greatest  width  at  proximal  end  28  mm. 

greatest  width  at  distal  end  36mm. 

least  diameter  of  shaft  16  mm. 

The  femur  belongs  to  the  type  specimen  which  is  about 
5%  larger  than  the  other  specimens.  This  bone  is  long 
and  rather  slender,  with  the  greater  trochanter  rising  well 
above  the  head,  which  is  rounded,  on  a  short  neck,  and 
has  the  ligamentary  pit  on  the  posterior  margin.  The 
thick,  rugose,  greater  trochanter  bends  in  over  the  head 
at  its  upper  end.  The  lesser  trochanter  is  relatively  small, 
and  prolonged  into  a  ridge.  Unfortunately  the  third  tro- 
chanter is  broken  off  in  my  specimen.  The  digital  fossa 
is  extremely  large  and  deep.  Proximally  the  shaft  is 
flattened,  but  becomes  rounded  distally.  Just  above  the 


NOTODIAPHORUS  CRASSUS 


35 


condyles  there  is  a  deep  rugose  pit  for  the  plantaris  muscle, 
and  on  the  anterior  side  the  suprapatellar  fossa  is  well 
marked.  The  condyles  are  placed  a  trifle  obliquely;  the 
internal  one  being  shorter  and  with  a  rounded  articular 
face,  the  external  condyle  being  longer,  and  with  a  flat- 
tened articular  face  which  slopes  obliquely  inward. 

Of  the  tibia,  only  the  distal  end  is  preserved.  This  in- 
dicates a  rather  slender  bone,  with  a  shal- 
low, fairly  wide  concavity  for  the  external 
astragular  trochlea,  and  a  narrower  and 
deeper  concavity  for  the  internal  astragu- 
lar trochlea.  O/i  the  internal  side  of  the 
tibia  there  is  a  rugose  surface  for  the  fibula. 

An  isolated  lower  end  of  a  fibula  indi- 
cates a  slender  bone,  enlarged  distally 
where  it  comes  in  contact  with  the  tibia. 
The  fibula  carries  on  its  inner  face  a  mod- 
erately large  facet  for  the  external  side 
of  the  astragulus,  and  on  the  distal  end  a 
wider  one  for  contact  with  the  calcaneum. 

The  tarsus  is  compactly  built,  wider 
than  that  of  Diadiaphorus,  because  the 
external  digits  are  not  as  much  reduced. 
This  especially  shows  in  the  greater  de-  Fig.  9.  Distal  end  of  teft 

t  c        ,  1-1  i      ,  i  tibia — */2  natural  size. 

velopment  of   the  cuboid  and   the  meso- 

cuneiform,  but  in  other  features  it  is  similar  to  that  of  its 

descendant. 

The  astragulus  is  a  very  characteristic  bone.  The  trochlea 
is  asymetrical,  the  external  condyle  rising  higher  than  the 
internal,  and  the  median  groove  being  wide  and  shallow. 
On  the  nearly  vertical  outer  face  of  the  astragulus,  there 
is  a  semicircular  band-like  facet  for  the  fibula.  The  trochea 
extends  well  around  the  top  of  the  bone,  allowing  a  wide 
movement  of  the  foot.  The  neck  of  the  astragulus  is  long 
and  wide,  carrying  a  broad  flattened  head,  with  its  con- 
vex facet  for  the  navicular,  covering  the  entire  end.  On 


THE  DESEADO  FORMATION  OF  PATAGONIA 


Fig.  10.  Left  pes,  dorsal  side,  ungual 
phalanx  from  specimen  No.  3275 — 1/2 
natural  size. 


NOTODIAPHORUS  CRASSUS  37 

the  plantar  side  are  the  most  marked  features.  The 
ectal  facet  is  in  two  planes,  the  anterior  portion  being 
bent  down  to  nearly  right  angles  with  the 
posterior,  which  seems  to  be  characteristic 
of  this  Diadiaphorus  series.  The  susten- 
tacular  facet  also  is  characteristic,  being 
gently  rounded  and  extending  clear  to  the 
navicular  facet  on  the  head,  in  Diadia- 
phorus becoming  actually  confluent  with  c 

,  Fig.  n.  Leftastragulus 

the   naVlCUlar   facet.        Just    at    the  edge  Of     Plantar  side:  a,  ectal  facet 

J  — 1/2  natural  size;  b,  sus- 

this  sustentacular  facet  is  a  tiny  surface   foSord.facet;  C(facet 
where  the  astragulus  rubs  on  the  cuboid, 
the  only  case,  as  far  as  I  am  aware,  where  this  occurs  in 
any  Litopterna. 

The  calcaneum  is  long  and  slender,  the  tuber  being  but 
slightly  enlarged,  its  sustentacular  facet  being  a  broad 
oval  surface,  while  the  ectal  facet  is  in  two  planes  to  cor- 
respond to  that  on  the  astragulus.  The  facet  for  the  cuboid 
is  at  the  distal  end,  but  is  unusually  oblique,  its  inner 
margin  sloping  up  almost  to  the  sustentacular  facet.  It 
is  this  slope  which  brings  the  cuboid  in  contact  with  the 
astragulus. 

The  navicular  is  broad  and  low,  with  a  prominent  hook 
behind.  On  its  upper  face  there  is  only  the  broad  facet 
for  the  astragulus  head;  on  the  lower  face  are  three  facets, 
externally,  a  large,  more  or  less  triangular  area,  for  the 
ectocuneiform;  medianly  a  smaller  similar  facet  for  the 
mesocuneiform;  and  on  the  internal  side,  sloping  up  onto 
the  internal  face,  a  small  facet  for  the  reduced  endocunei- 
form.  On  the  external  face  of  this  bone  there  is  a  tiny 
beveled  facet  for  the  cuboid. 

The  endocuneiform  is  a  large  scale-like  ossicle  articulating 
on  the  lateral  internal  face  of  the  navicular,  and  over- 
lapping markedly  the  inner  surface  of  Metatarsus  II. 

The  mesocuneiform  is  considerably  reduced  in  size, 
carrying  a  broad  flat  facet  on  the  upper  surface  for  the 


38  THE  DESEADO  FORMATION  OF  PATAGONIA 

navicular,  and  a  shallow  saddle-like  one  below  for  Mt. 
II,  which  is  entirely  carried  by  this  bone. 

The  ectocuneiform  is  considerably  larger  than  the  meso-  . 
cuneiform,   resting  above  on  the  navicular,   and  carrying 
below  the  whole  of  Mt.   III.     On  its  inner  side  are  two 
facets  which  rub  against  the  upper  end  of  Mt.  II. 

The  cuboid  is  a  nodular  bone,  its  upper  surface  occupied 
by  the  facet  for  the  calcaneum,  the  lower  face  occupied  by 
the  facet  for  Mt.  IV,  while  on  the  external  side 
there  is  a  tiny  beveled  facet  for  the  vestige  of 
Mt.  V,  and  with  a  small  boss  on   the  inner 
surface  which  carries  two  tiny  facets,  the  upper 
Fig.  12.  cuboid    one  for  the  ectocuneiform  and  the  lower  for  the 

internal  side  to 

navicular.     On  this  same  inner  side,  near  the 


for  navicular  ^c    top  there  is  a  second  small  boss,  which  carries 
tilr    &  tiny  facet   to  rub  on   the   astragulus,   and 
°fecetfar    below  that  a  second  tiny  facet  for  the  navicular. 

mesocunieforms  r^i  .  r     ,  •..    .  .    .  . 

—  i/2  natural  I  he  pes  consists  of  three  digits,  with  a  vestige 
of  Mt.  V.  Of  the  developed  digits,  the  median 
one  is  the  largest,  but  the  two  lateral  digits  are  only  a  little 
smaller  and  were  functional,  so  that  this  form  was  truly 
three-toed,  comparable  in  the  digital  reduction  to  Meso- 
hippus. 

Mt.  II  is  flattened  above  but  soon  broadens  into  a 
rounded  shaft  of  considerable  length,  on  the  end  of  which 
is  the  articular  trochlea,  with  the  carina  extending  onto 
both  the  upper  and  lower  surface,  being,  however,  higher 
on  the  lower  surface.  Proximally  this  bone  is  overlapped 
by  the  endocuneiform,  is  carried  by  the  small  mesocunei- 
form,  and  also  articulates  on  the  inner  side  of  the  ecto- 
cuneiform. Mt.  Ill  is  also  compressed  at  the  upper  end, 
broadens  below,  and  carries  an  articular  trochlea  similar 
to  that  of  Mt.  II,  except  that  the  carina  does  not  extend 
so  far  onto  the  upper  surface.  Like  Mt.  II,  Mt.  IV  is 
carried  high  on  the  tarsus,  and  therefore,  though  nearly  as 
long  as  Mt.  Ill,  it  does  not  have  the  same  effective  length. 


NOTODIAPHORUS  CRASSUS  39 

Proximally  it  articulates  entirely  on  the  cuboid;  distally 
it  has  a  trochlea  similar  to  that  of  Mt.  II,  the  carina  extend- 
ing onto  the  dorsal  surface.  While  Mt.  V  is  lacking,  it  is 
clearly  indicated  that  a  vestige  of  it  should  have  been 
present,  as  there  is  a  tiny  articular  surface  for  it  on  the 
cuboid,  and  a  rugose  surface  on  the  outside  of  Mt.  IV. 

The  phalanges  are  long  and  have  the  articular  ends 
swollen  somewhat  as  in  camels.  The  phalanges  of  the 
first  row  are  nearly  equal  in  size,  each  with  the  proximal 
trochlea  deeply  notched  for  the  carina  of  the  metatarsus; 
and  with  the  distal  trochlea  simple,  though  slightly  concave 
from  side  to  side,  and  reflexed  well  onto  the  dorsal  surface. 
The  phalanges  of  the  second  row  are  shorter  and  simpler, 
and  somewhat  depressed  distally.  The  ungual  phalanges 
are  flattened  from  top  to  bottom,  of  moderate  size,  some- 
what longer  than  wide,  and  without  any  indications  of  a 

cleft. 

MEASUREMENTS,  SPECIMEN                       No.  3287    No.  3275 

Femur,  length  289  mm. 

diameter  across  gr.  trochanter  80  mm. 

diameter  of  middle  of  shaft  32  mm. 

diameter  of  distal  end  7°  mm. 

Tibia,  diameter  of  shaft  28  mm.     24  mm. 

diameter  at  distal  end  38  mm-     36  mm. 

Calcaneum,  length  103  mm.     96  mm. 

width  36  mm.     35  mm. 

Astragulus,  length  48  mm.     44  mm. 

width  38  mm.     35  mm. 

Metatarsus  II,  length  114  mm.   105  mm. 

Metatarsus  III,  length  122  mm.   114  mm. 

Metatarsus  IV,  length  no  mm.  101  mm. 

Phalanx  I  of  digit  III,  length  49  mm- 

Phalanx  2  of  digit  III,  length  27  mm. 

Phalanx  3  of  digit  III,  length  29  mm. 

D cut er other ium  Ameghino 

Deuterotherium  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  633. 
Deutorotherium  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  452. 

This  genus  was  first  founded  on  a  clacaneum  and  a  bit 
of  the  mandibular  symphysis,  to  which  were  added,  later, 


40  THE  DESEADO  FORMATION  OF  PATAGONIA 

both  the  upper  and  lower  premolar  and  molar  teeth.  As 
far  as  it  is  known,  it  is  distinguished  by  the  upper  molars 
lacking  the  metaconule  entirely,  and  being  approximately 
like  those  of  Thaotherium.  The  dental  formula  is  given 
by  Ameghino  as  2043*  <tne  same  as  Thaotherium.  But 
one  species  has  been  described. 

Deuterotherium  distichum  Ameghino 

We  did  not  find  this  species,  but  the  teeth  assigned  to 

it  are  very  characteristic, 
and  so  I  reproduce  Amegh- 
ino's  figure  of  them.  The 
species  is  distinguished  by 

Fig.  13.  Upper  pm.  3-m.  3    of  the  left  side — 

its  size  primarily.     The  fol- 
lowing are  the  chief  measurements  given. 

Upper  dentition,  pm.  3  to  m.  3,  length  50  mm. 

Lower  dentition,  inc.  I  to  m.  3,  length  80  mm. 

Macrauchenidae 
( =  Mesorhinidae  Amegh.) 

This  family  is  distinguished,  first,  by  the  complete 
dental  series  in  which  none  of  the  anterior  teeth  are  devel- 
oped into  tushes;  by  the  nasals  being  shortened,  apparently 
in  connection  with  the  development  of  a  proboscis;  by 
its  long  neck;  and  by  its  feet  being  permanently  tridactyl, 
all  the  three  toes  being  equally  developed.  In  the  Deseado 
it  is  infrequent,  but  to  it  Ameghino  has  assigned  two  genera; 
Protheosodon,  which  he  describes  as  similar  to  Theosodon, 
but  which  I  find  much  nearer  to  the  Casamayor  repre- 
sentatives of  this  family,  such  as  Lambdacomis,  though  it 
doubtless  belongs  to  the  series  which  is  represented  in  the 
Santa  Cruz  by  Theosodon.  He  has  also  made  a  second 
genus,  Conioptothermm,  which  represents  a  large  Macrau- 
chenid,  equal  in  size  to  Theosodon.  This  genus  is  based 
on  the  calcaleum  and  astragulus  and  seems  to  be  rare. 


PRIMITIVE  MACRAUCHENID  41 

Protheosodon  Ameghino 

Protheosodon,  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  1 8,  p.  453. 
Protheosodon,  Amegh.,  1904,  Anal.  Mus.  Nac.  B.A.,  ser.  3,  t.  3,  p.  421. 

This  genus  was  founded  on  an  upper  second  molar  and 
the  fourth  premolar.  I  figure  m.  2,  and  it  will  be  seen  that 
they  represent  a  form  little  specialized,  resembling  in  the 
low  crowns,  plump  cusps,  and  presence  of  both  protoconule 
and  metaconule,  the  Casamayor  types,  such  asLambdaconus 
or  Didolodus,  rather  than  the  advanced  type  like  the  Santa 
Cruz  genus,  Theosodon.  We  found  a  specimen  with  the 
lower  jaws  complete  and  with  the  hind  limb  complete, 
which,  I  am  confident,  is  the  same  form,  though  I  can  not 
duplicate  any  tooth,  for  we  found  no  upper  teeth;  but  in 
size  they  agree  with  Protheosodon,  also  in  the  primitive 
character;  and,  were  one  from  the  lower  teeth  to  postulate 
the  upper,  they  would  be  just  such  as  Ameghino  has  de- 
scribed under  the  name  Protheosodon.  Therefore  I  have 
assigned  my  material  to  this  genus  and  species.  It  adds 
to  the  genus  characters  the  fact  that  this  form  had  a  shorter 
back,  relatively  as  well  as  actually,  than  Theosodon;  that 
the  hind  limb,  at  least,  was  much  heavier  and  also  shorter 
than  that  of  Theosodon,  especially  in  the  metatarsal  region 
where  relatively  the  elements  are  only  about  half  as  long. 
The  pes  is  of  the  same  character  as  in  Theosodon,  but  again 
relatively  much  shorter.  I  believe  in  Prothesodon  we  have 
to  do  with  a  form  intermediate  between  Lambdaconus  and 
Theosodon,  and  nearer  to  the  former. 

Protheosodon  coniferus  Ameghino. 

P.  coniferus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  453. 

Ameghino  has  described  two  upper  teeth.  Specimen 
No.  3001  of  the  Amherst  Collection  from  the  Chico  del 
Chubut  River,  west  of  Puerto  Visser,  adds  to  this  the 
knowledge  of  twelve  vertebrae  (seven  dorsal  and  five  lum- 
bar), the  lower  dentition  complete,  the  left  hind  limb 


THE  DESRADO  FORMATION  OF  PATAGONIA 


complete,  and  the  right  hind  limb  complete  except  for 
the  femur.  In  general,  the  animal  is  about  |  the  size  of 
Theosodon  garrettomm,  but  in  parts  varies 
from  this  as  follows.  The  lower  jaw  is  |, 
the  vertebrae  are  f  in  length,  the  hind  leg 
is  |  in  length  but  f  in  diameter  of  bones, 
while  the  metatarsus  is  only  J  in  length. 
Fig.  14.  upper  mo-  This  makes  an  almost  plantigrade  form  of 

lar.    2  of  the  right    i  < 

side— natural  size,  heavy,   clumsy  proportions. 

after  Ameghino.  „  r      ,  ... 

Of  the  upper  dentition  we  know  only  what 
Ameghino  has  given  us.  The  molar  is  distinguished  by 
the  presence  of  both  the  protoconule  and  metaronule,  by 
the  development  of  the  posterior  ringulum  and  by  the 
presence  of  three  external  styles. 


MEASUREMENTS 

Upper  premolar  4,  length  12  mm.,  width  15  mm. 
Upper  molar  2,  length  14  mm.,  width  17  mm. 

In  the  lower  dentition,  none  of  the  teeth  are  reduced, 
and  all  are  in  a  continuous  series,  except  that  there  is  a 


Fig.  15.  Right  lower  dentition — natural  size. 

small  diastema  either  side  of  pm.  i.  The  incisors  are 
simple,  compressed  teeth,  with  but  a  trace  of  a  cingulum. 
The  canine  is  incisiform  and  a  trifle  larger  than  the  incisors. 
Premolar  I  is  also  incisiform,  and  is  isolated  by  a  small 
diastema  on  either  side.  The  second  premolar  is  longer 
and  wider  than  the  first,  and  begins  to  show  molariform 
characters,  the  anterior  portion  being  composed  of  a  high 
compressed  cusp,  the  posterior  portion  by  a  low  crescent 
on  which  but  one  cusp  is  fully  developed.  The  third  pre- 
molar is  composed  of  two  complete  crescents,  and  has  the 


PROTHEOSODON  CONIFERUS  43 

"pillar"  already  developed  opposite  the  posterior  end  of 
the  back  crescent.  In  fact,  the  tooth  is  molariform,  except 
as  to  the  tiny  extra  cusp  found  on  the  molars.  Premolar 
4  is  more  completely  molariform  consisting  of  the  same 
parts  as  the  preceding  tooth. 

The  molars  may  be  distinguished  by  the  presence  of  a 
tiny  median  cusp  on  the  rear  of  the  tooth,  behind  the  cres- 
cent, which,  when  the  tooth  is  worn,  makes  a  median  spur 
to  the  rear.  In  both  the  premolars  and  molars,  the  teeth 
are  characterized  by  their  plumpness,  and  the  isolation 
and  lowness  of  the  cusps. 


Fig.  16.  Right  mandible — 1/2  natural  size. 

The  two  halves  of  the  lower  jaw  are  completely  fused  at 
the  symphysis.  The  horizontal  ramus  is  thick,  but  low 
dorso-ventrally,  giving  the  appearance  of  a  slender  jaw. 
The  posterior  angle  is  prolonged  backward  and  bent  in- 
ward. The  fossa  for  the  masseter  muscle,  while  large,  is 
but  faintly  outlined.  The  ascending  ramus  hardly  rises 
above  the  level  of  the  teeth,  except  as  the  slender  coronoid 
projects  to  a  good  height  above  the  articular  condyle 
and  curves  backward  over  it. 


44  THE  DESEADO  FORMATION  OF  PATAGONIA 

MEASUREMENTS 

Lower  dentition,  total  length  114  mm. 

incisors,  length  20  mm. 

canine,  length  8  mm. 

premolar  2  to  4  35  mm. 

molar  I  to  3  42  mm. 

Mandible,  total  length  188  mm. 

height  under  molar  I  24  mm. 

height  to  top  of  coronoid  95  mm. 

The  dorsal  vertebrae  have  short,  wide,  and  somewhat 
depressed  centra  (in  this  individual  the  epiphyses  are 
free,  though  this  is  the  only  indication  of  youth).  The 
lower  rib  facets  are  small,  that  on  the  posterior  margin  of 
the  centrum  being  a  mere  streak,  while  the  one  on  the 
anterior  margin  is  narrow.  The  upper  rib  facet  is  a  rounded 
convex  surface  on  the  end  of  a  short  stout  transverse  proc- 
ess. The  prezygapophyses  are  convex  surfaces,  wide 
transversely,  but  narrow  in  the  anteroposterior  direction, 
while  the  postzygapophyses  are  correspondingly  narrow 
concave  facets  under  the  rear  of  the  spines.  The  spines 
are  thin  and  high,  and  the  neural  canal  is  nearly  circular  in 
section. 

The  lumbar  vertebrae  have  laterally  compressed,  deep 
centra,  with  very  long  transverse  processes,  shorting  spines, 
and  zygapophyses  of  the  subcylindrical  interlocking  type. 
In  all  their  features  the  vertebrae  resemble  those  of  Theo- 
sodon,  being  nearly  as  highly  specialized  and  in  the  same 
manner. 

MEASUREMENTS  OF  TYPICAL  VERTEBRAE 

Dorsal  vertebra  No.  7,  length  23  mm. 

width  of  centrum  22  mm. 

Dorsal  vertebra  No.  9,  length  28  mm. 

Lumbar  vertebra  No.  2,  length  29  mm. 

Lumbar  vertebra  No.  2,  width  of  centrum  24  mm. 

Lumbar  vertebra  No.  2,  width  across  transverse  processes  160  mm. 

The  femur  is  short  and  very  stocky.  The  rounded  head 
is  carried  on  a  short  neck,  and  does  not  rise  nearly  as  high 
as  the  greater  trochanter,  the  sulcus  for  the  round  liga- 


PROTHEOSODON  CONIFERUS 


45 


ment  being  a  broad,  deep  notch  on  the  posterior  margin. 
The  greater  trochanter  is  rugose,  heavy,  and  high,  but  not 
incurved  at  the  top.  The  lesser  trochanter  is  a  small,  thin 
ridge  well  below  the  head.  The  third  trochanter  is  a  large, 
thin  process,  projecting  almost  directly  backward,  though 
curved  inward  at  the  end,  and  is  situated  well  below  the 


Fig.  17.  Left  femur  anterior  side 
— i  /2  natural  size. 


Fig.   1 8.    Tibia    and    fibula 
(right) — 1/2  natural  size. 


middle  of  the  bone.  The  shaft  of  the  femur  is  flattened 
above,  but  thick,  and  changes  in  the  lower  part  to  subcy- 
lindrical.  The  condyles  are  small,  subequal  in  size,  and 
widely  separated,  while  the  rotular  trochlea  is  relatively 
wide  and  shallow. 

The  tibia  is  about  three-fourths  the  length  of  the  femur, 
very  stocky  and  heavily  built.     On  the  proximal  end,  the 


THE  DKSEADO  FORMATION  OF  PATAGONIA 


convex  external  condyle  is  much  narrower  anteroposte- 
riorly  than  the  larger  and  slightly  concave  internal  condyle. 
The  low  spine  is  bifid.  A  cnemidial 
crest  extends  to  the  middle  of  the  hone. 
On  the  distal  end,  the  broad  and  shal- 
low external  articular  facet  is  separated 
from  the  narrow  and  deeper  internal 
facet  by  a  low  intercondylar  ridge. 
The  fibula  is  fused  to  the  tibia  at 
the  upper  end,  but  is  free  below,  being 
approximated  to  the  tibia  along  a  rugose 
surface  nearly  an  inch  long.  This  bone 
is  rather  slender  and  strongly  bowed 
outward.  Distally,  there  is  a  large 
facet  for  the  outside  of  the  astragulus, 
the  back  part  of  which  rests  on  the 
calcaneum.  This  is  peculiarly  devel- 
oped so  that  the  articulation  represents 
what  is  two  separate  facets,  the  one  for 
the  outside  of  the  astragulus  the  other 
for  the  calcaneum.  Here,  however,  they 
are  blended. 

While  in  general  the  tarsus  is  similar 
to   that  of    Theosodon,    there  are  sonic 
fni8houtfr'from  marked  contrasts.     The  astragulus  has 

thelef  -i/2  natural     an  asymetrical  tTO- 

chlea  with  a  shallow 
groove,  the  external  condyle  being  higher 
and  narrower  than  the  internal.  The 
head  is  depressed  in  the  dorso-plantar 

I  ,  111  FiR-     2O-     Astragulus 

plane,    is    carried    on    a   moderately   long  plantar  side— a,  extor- 

tiii  r  r  nal  facet;    b,  sustentac- 

neck,  and  has  a  broad  convex  facet  for  "jar  facet— 1/2  natural 
the  navicular  on  which  alone  it  articu- 
lates. On  the  plantar  side,  the  ectal  facet  is  broadly  oval 
and  slightly  concave,  differing  from  that  of  Theosodon  in 
having  no  sulcus  dividing  it  into  lobes.  The  broad  sus- 
tentacular  facet  is  slightly  convex,  and  widely  separated 


PROTHEOSODON  CONIFERUS  47 

from  the  ectal.  On  the  external  side  the  astragulus  carries 
an  expanded  articular  facet  for  the  inner  side  of  the  fibula, 
which,  instead  of  being  vertical,  is  expanded  below,  mak- 
ing an  oblique  face  which  is  continuous  with  the  fibular 
facet  on  the  calcaneum.  In  this  feature  Protheosodon  is, 
as  far  as  the  feet  are  known,  unique. 

The  calcaneum  is  a  long  bone  with  a  club-shaped  expan- 
sion of  the  upper  end.  The  fibular  facet  is  small,  being 
continuous,  as  above  described,  with  that  on  the  outer 
side  of  the  astragulus.  On  the  face  toward  the  astragulus, 
the  ectal  facet  is  broadly  convex  (not  divided  as  in  Theo- 
sodoti),  while  the  sustentacular  facet  is  slightly  concave. 
The  distal  end  is  occupied  by  the  large  concave  facet  for 
the  cuboid. 

The  navicular  is  of  moderate  height,  with  a  prominent 
hook  behind.  On  the  upper  surface  is  only  the  broad, 
deep  facet  for  the  astragulus;  while  the  lower  surface  is 
divided  into  facets  for  the  three  cuneiforms,  and  the  ex- 
ternal distal  margin  is  beveled  to  make  a  narrow  facet  for 
the  cuboid.  This  navicular  differs  from  that  of  Theosodon 
in  that  the  facet  for  the  ectocuneiform  is  not  cut  step-like 
into  its  external  face. 

The  endocuneiform  is  a  small  scale-like  bone  with  a 
narrow  facet  on  the  navicular,  and  overlapping  the  inner 
side  of  Mt.  II.  The  mesocuneiform  is  small,  with  a  flat 
facet  above  for  the  navicular,  and  a  convex  one  below  for 
Mt.  II,  which  is  carried  wholly  on  this  bone.  The  ecto- 
cuneiform is  far  the  largest  of  these  three  bones,  and  car- 
ries a  broad  facet  above  for  the  navicular,  a  similar  one 
below  for  Mt.  Ill,  a  small  facet  on  the  internal  side  for  the 
mesocuneiform  and  a  second  one  below  that  for  the  side 
of  Mt.  II,  while  externally  there  are  facets  for  the  cuboid 
and  for  the  side  of  Mt.  IV. 

The  cuboid  is  large,  the  external  side  being  longer  than 
the  internal.  The  upper  surface  is  entirely  occupied  by 
the  facet  for  the  calcaneum,  while  the  lower  face  is  mostly 
devoted  to  the  facet  for  Mt.  IV,  with  a  narrow  streak  on  the 


48  THE  DESEADO  FORMATION  OF  PATAGONIA 

external  margin  for  the  vestige  of  Mt.  V.  The  internal 
face  carries  a  boss  beveled  above  by  the  facet  for  the  navic- 
ular,  and  below  by  the  facet  for  the  ectocuneiform. 

All  the  metatarsals  are  short  and  heavy  as  compared 
with  those  of  Theos^don.  Mt.  II  is  compressed  above, 
but  enlarges  below  into  a  subcylindrical  bone,  ending  in  an 
extensive  articular  trochlea  for  the  phalanx,  the  trochlea 
carrying  a  carina  which  extends  into  the  upper  surface  of 
the  articular  area.  Proximally,  it  is  so  closely  approxi- 
mated to  the  adjacent  metatarsus  that  these  could  have 
had  very  little  independent  movement.  On  the  upper 
internal  surface,  there  is  a  roughened  area,  where  the  endo- 
cuneiform  overlaps  this  bone.  Mt.  Ill  is  slightly  heavier 
than  the  others.  On  the  distal  end,  its  articular  trochlea 
extends  well  onto  the  dorsal  surface,  as  does  also  the  carina. 
Mt.  IV  is  a  trifle  shorter  than  the  others  and  stouter. 
Mt.  V  is  absent  but  its  former  presence  is  indicated  by 
the  beveled  facet  on  the  cuboid,  and  by  the  small  roughened 
surface  on  Mt.  IV. 

The  phalanges  of  the  third  digit  are  a  trifle  heavier  than 
those  of  the  other  two  digits,  but  of  approximately  the 
same  lengths.  The  ungual  phalanges  were  broad  com- 
pressed hoofs,  without  traces  of  clefts. 

MEASUREMENTS  OF  THE  HIND  LIMB 

Femur,  length  from  the  head  177  mm. 

greatest  proximal  width  70  mm. 

greatest  distal  width  56  mm. 

Tibia,  total  length  149  mm. 

greatest  proximal  width  52  mm. 

greatest  distal  width  56  mm. 

Fibula  diameter  of  shaft  9  mm. 

Astragulus,  length  23  mm. 

width  24  mm. 

Calcaneum,  length  62  mm. 

Metatarsus  II,  length  45  mm. 

Metatarsus  III,  length  48  mm. 

Metatarsus  IV,  length  42  mm. 

Phalanx  I  of  digit  III,  length  24  mm. 

Phalanx  2  of  digit  III,  length  16  mm. 

Phalanx  3  of  digit  III,  length  I?  mm. 


50  THE  DESEADO  FORMATION  OF  PATAGONIA 

RESTORATION 

In  order  to  get  a  comparison  of  what  is  known  of  this 
form  with  Theosodon  I  have  outlined  a  restoration  of  the 
animal  as  a  whole,  realizing  that  some  essential  parts  are 
lacking,  but  the  general  proportions  can  hardly  vary  greatly 
from  those  given.  It  appears,  first,  that  this  form  has 
an  unusually  short  back.  Though  the  limbs  and  lower 
jaw  are  |  the  length  of  those  of  Theosodon  garrettorum, 
the  vertebrae  are  \  as  long.  I  have  assumed  that  the 
number  of  vertebrae  would  prove  to  be  the  same  as  in 
Theosodon.  While  the  limb  bones  are  f  as  long  as  in  the 
Theosodon,  they  are  relatively  half  again  as  heavy  and  with 
the  processes  much  more  developed.  The  greatest  differ- 
ence is  found  in  the  tarsus  which  is  only  ^  as  long  as  that 
of  Theosodon,  though  relatively  as  heavy,  and  the  foot 
was  carried  in  a  nearly  plantigrade  position  the  heel  raised 
but  a  little  from  the  ground,  though  the  anticular  ends  of 
the  metatarsals  and  the  phalanges  indicate  that  there  was 
a  considerable  freedom  of  movement  of  the  various  ele- 
ments. The  form  seems  to  be  fairly  close  to  the  ancestral 
types  such  as  Lambdaconus  of  the  Casamayor,  the  limbs 
of  which,  however,  are  entirely  unknown,  but  I  should 
expect  that  when  found  these  earlier  forms  would  prove 
to  be  approximately  plantigrade. 

Coniopternium  Ameghino 

Coniopternium  Amegh.,  1895  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  632. 
Coniopternium  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  453. 

The  genus  is  based  on  a  calcaneum  and  astragulus  of 
the  macrauchenid  type,  but  of  unusually  large  size.  The 
real  generic  characters  are  not  evident  in  the  description, 
but  the  presence  of  these  bones,  and  of  three  cervical  verte- 
brae, which  wre  also  found,  indicating  a  macrauchenid  of 
about  the  same  size,  are  evidence  that  a  form  larger  than 
the  Santa  Cruz  representatives  will  turn  up  in  the  Deseado 
beds,  for  which  this  name  may  be  reserved.  The  material 
is  described  under  the  specific  name  C.  andinum. 


TRICOELODUS  51 

Adianthidae  Ameghino 

This  family  is  based  primarily  on  the  genus  Adianthus 
of  the  Santa  Cruz  to  contain  some  macrauchenid-like 
forms  which,  however,  are  of  much  smaller  size,  and  differ- 
entiated by  the  narrow  character  of  the  teeth  and  their 
early  tendency  to  hypsodonty.  It  seems  to  be  a  valid 
series  of  dwarf  types,  which  are  all  scarce  and  known  only 
by  the  most  fragmentary  remains.  Two  genera  are  de- 
scribed from  the  Deseado,  Tricoelodus,  peculiar  in  having 
the  posterior  lobe  of  the  lower  molars  somewhat  subdivided 
so  that  the  tooth  appears  three-lobed;  and  Proadianthus, 
known  only  by  premolars  which  however  show  an  unusual 
development  of  the  styles  on  the  inner  side  of  the  teeth. 

• 
Tricoelodus  Ameghino 

Tricoelodus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  454. 

The  genus  is  based  primarily  on  the  three-lobed  char- 
acter of  the  molars,  which  is  a  secondary  effect  of  an  infold- 
ing on  the  inner  side  of  the  posterior  lobe.  They  are  rooted, 
but  strongly  hypsodont.  The  margins  of  the  crescents 
are  well  developed  and  the  '  'pillar"  is  a  prominent  feature 
in  the  posterior  crescent. 

Tricoelodus  bicuspidatus  Ameghino 

T.  tricuspidatus  Amegh.,  loc.  cit.  above. 

The  species  is  the  only  one  known  of  the  genus,  and 
its  features  are  those  of  the  genus.     The 
_   _  following  measurements  indicate  the  size, 

Tig.  22.  Lower  right  lower  pm.  3  to  m.  I,  25  mm.;  height  of  the 
mandible  under  molar  I  is  12  mm. 


Proadianthus  Ameghino 

Proadianthus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  455. 

This  genus  is  known  only  by  the  last  two  premolars  of 
the  lower  jaw,  which  are  compressed  and  moderately  high. 


52  THE  DESEADO  FORMATION  OF  PATAGONIA 

The  two  crescents  are  markedly  separated  by  a  cleft  from 
the  external  side  of  the  tooth,  opposite  to  which  is  a  high 
denticle,  made  by  the  fusion  of  the  two  ends  of  the  cres- 
cents wrhere  they  come  together. 

Proadianthus  excavatus  Ameghino 

P.  excavatus.  Amegh.,  loc.  cit.  above. 

The  species  is  based  on  the  two  lower 
premolars  described  above.  I  reproduce 
the  figure  given  by  Ameghino.  The 
measurements  are:  length  of  pm.  3  and 

i      •     i  r  i«t   i  Fig-  23-  Lower   right 

4,  10  mm. ;  height  of  mandible  under  pm.  pm.  3  and  4— natural 

size,  after  Ameghino. 

4,  8  mm. 


CHAPTER  V 

TYPOTHERIA 

In  the  Deseado  beds  this  group  of  running  and  hopping 
animals  is  well  represented,  making  about  14%  of  the 
Amherst  collection,  and  varying  in  size  from  a  little  larger 
than  a  rat  to  larger  than  a  sheep. 

The  group  all  have  the  front  teeth  modified  into  cropping 
or  gnawing  types,  which  grow  permanently  from  persistent 
pulps;  and  the  back  teeth  also  growing  through  the  whole 
or  a  large  part  of  life,  and  also  rootless,  the  crowns  being 
variously  infolded  to  make  grinding  surfaces.  The  skull 
is  flattened  above,  and  abruptly  truncated  behind;  the 
cranium  being  large  and  swollen,  the  facial  portion  broad 
above  and  excavated  on  the  sides.  The  orbits  are  centrally 
located,  of  considerable  size,  and  unbounded  behind.  The 
tympanic  bulla  is  swollen  and  may  be  hollow  or  filled  with 
cancellous  tissue.  This  cavity  of  the  tympanic  is  con- 
tinued above  and  expands  in  the  upper  part  of  the  squa- 
mosum,  making  a  swollen  capsule  on  either  side  of  the  back 
of  the  cranium.  The  openings  of  the  auditory  meatus 
are  well  back  and  in  a  tubular  growth  of  the  periotic  which 
is  directed  back,  and  upward  in  an  entirely  characteristic 
manner.  The  strong  paroccipital  processes  project  far 
below  the  base  of  the  carnium.  The  concave  palate  is 
wide  and  carried  well  back  behind  the  teeth  ending  in 
two  strong  pterygoid  processes.  The  mandible  is  deep, 
especially  the  back  portion ;  has  a  slender  coronoid  process, 
and  a  small  rounded  articular  condyle  which  would  seem 
to  indicate  a  forward  and  backward  motion  of  the  jaws. 
On  account  of  the  agreement  with  these  general  features, 
I  have  placed  among  the  Typotheria  the  forms  which  Ame- 
ghino  classified  as  Hyracoidea. 


54  THE  DESEADO  FORMATION  OF  PATAGONIA 

While  agreeing  in  the  above  general  features,  there  is 
great  variation  among  the  various  forms.  The  first  upper 
and  lower  incisor  may  be  greatly  enlarged  or  of  normal 
size.  There  is  a  tendency  for  the  third  upper  and  lower 
incisor,  the  canines,  and  the  first  premolars  to  be  reduced 
and  disappear,  and  all  intermediate  grades  are  found. 
In  the  molars  there  is  a  regular  tendency  toward  simplifi- 
cation ;  so  that  in  the  upper  molars  of  the  earlier  forms  there 
is  a  deep  inner  fold  and  a  more  moderate  outer  fold,  either 
or  both  of  which  may  disappear  completely,  though  in 
one  series  the  fold  seems  to  have  been  accentuated  instead 
of  lost.  The  feet  may  be  adapted  to  running  or  hopping. 

In  the  Deseado  and  Santa  Cruz  material,  four  series 
of  modifications  may  be  distinguished  which  I  have  desig- 
nated as  families;  (i)  the  Archaeohyracidae,  primitive 
forms  in  which  the  incisors  are  little  enlarged,  with  inner 
and  outer  folds  on  the  molars,  those  on  the  inner  side  of 
the  upper  molars  being  very  deep,  bulla  small,  feet  un- 
known; (2)  Inter atheriidae,  first  upper  and  lower  incisors 
rooted  and  of  moderate  size,  inflexions  on  both  the  inner 
and  outer  sides  of  the  molars,  bulla  large,  feet  adapted  to 
running;  (3)  Hegetotheriidae,  incisor  I  of  upper  and  lower 
dentition  greatly  enlarged  and  rootless,  molars  simplified, 
bulla  large,  feet  adapted  to  running  or  to  hopping;  (4) 
Etttrachytheridae,  large  forms  with  the  first  upper  and  lower 
incisor  enlarged  and  rootless,  the  upper  molars  with  the 
inner  fold  developed  and  bifurcated,  bulla  large,  feet 
unknown. 

For  comparison  of  the  various  genera,  they  are  charted 
on  page  55,  the  dental  character  being  used,  as  but  few 
have  the  skeleton  known,  which  is  especially  so  of  the  earlier 
genera. 

From  the  foregoing  chart  and  the  comparative  figures  of 
the  upper  and  lower  dentitions,  the  variety  and  at  the 
same  time  the  homogeneity  of  the  Typotheria  is  evident. 
The  gnawing  front  teeth  resemble  those  of  rodents,  espe- 


CHART  OF  TYPOTHERIA 


55 


AGE 

FORMULA 

CANINES 

U.  MOLARS 

LAST  i.  MOLAR 

I 
TOES 

Hegetotherium 

Santa  Cruz 

3143 

vestigal 

no  inner 
fold 

3-lobed 

cleft 

3143 

Prohegetotherium 

Deseado 

no  inner 
fold 

Pachyrukhos 

Santa  Cruz 

1033 

lacking 

no  inner 
fold 

3-lobed 

not 
cleft 

2033 

Propachyrucos 

Deseado 

slightly 
reduced 

3-lobed 

3143 

Prosotherium 

Deseado 

1043 

lacking 

simple  inner 
fold 

3-lobed 

slightly 
cleft 

pm.  simple 

2043 

Archaeophylus 

Deseado 

?  i  43 

rather 
large 

deep    inner 
fold,  slight 
outer  one 

Interatherium 

Santa  Cruz 

3143 
3143 

vestigal 

slight    inner 
and  outer 
folds 

2-lobed 

slightly 
cleft 

Protypotherium 

Santa  Cruz 

3143 

large 

deep  inner 
and  outer 
folds 

2-lobed 

slightly 
cleft 

closed  series 

3143 

Argyrohyrax 

Deseado 

3143 

large 

bifurcated 
inner  fold 

E  utrachy  therus 

Deseado 

3143 

lacking 

bifurcated 
inner  fold 

2-lobed 

2143 

Isoproedrium 

Deseado 

?   ?43 

Archaeohyrax 

Deseado 

3143 

large 

deep  inner 
fold,  slight 
outer  fold 

3-lobed 

3143 

Plagiarthrus 

Deseado 

2-lobed 

?  ?  43 

cially  in  the  genera  where  the  enamel  is  lacking  on  all  but 
the  front  face,  but  this  is  entirely  a  parallelism  and  there 
is  no  evident  phylogenetic  relationship.  As  to  affinities 
with  the  Hyracoidea,  Sinclair*  has  carefully  balanced 
them  and  finds  so  little  in  common  between  the  two  groups 

*Princeton  Expeditions  Reports,  Vol.  VI,  p.  7,  1909. 


56  THE  DESEADO  FORMATION  OF  PATAGONIA 

ml 


Fig.  24.  Comparative  series  of  upper  dentitions  of  Deseado  and  Santa  Cruz  Typotheria;  a,  Archaeohyrax  patagonicus; 
b,  Hegetotherium  mirabile;  c,  Prosotherium  garzoni;  d.  Pachrukhos  moyani:  e.  Archaeophylus  patrius;  /,  Interatherium 
extensum;  g  Protypotherium  australe;  h,  Argyrohyrax  proavus;  i,  Eutrachytherus  spegazzinianus — all  natural  size. 


LOWER  TEETH  OF  TYPOTHERIA 


58  THE  DESEADO  FORMATION  OF  PATAGONIA 

that  he  makes  them  a  separate  suborder.  I  find  certain 
features  in  common,  like  the  lophodont  dentition  with  the 
tendency  toward  hypsodont  incisors,  the  inflation  of  the 
tympanic  and  the  extension  of  this  up  into  the  periotic 
region,  and  the  general  arrangement  of  the  basicranial 
foramena.  On  the  other  hand,  there  are  also  numerous 
features  in  common  with  the  Toxodonts,  and  several  pecu- 
liar to  the  group,  so  that  I  would  feel  that  all  the  Notun- 
gulates  are  descended  from  the  Hyracoidea,  and  this  group 
has  developed  its  peculiarities  in  South  America,  retaining 
however  a  little  more  of  the  hyracoid  aspect. 

The  Archaeohyracidae  are  the  most  primitive  of  the 
Deseado  forms,  but  as  all  the  families  are  already  separated 
before  this  time  the  Deseado  genera  can  not  be  considered 
as  the  ancestral  ones,  though  they  seem  to  have  retained 
more  of  the  primitive  features. 

The  Inter aiheriidae  represent  an  offshoot  line  of  develop- 
ment in  which  the  incisors  are  not  much  enlarged  and  the 
infoldings  of  the  teeth  remain.  The  genus  Archaeophylus 
seems  to  be  directly  ancestral  to  the  Santa  Cruz  genera 
Interatherium  and  Proty pother ium.  In  the  family  Ilege- 
totheriidae  there  is  a  strong  tendency  for  the  incisors  to 
develop  into  very  large  gnawing  teeth,  while  the  lateral 
incisors,  the  canine  and  the  first  premolar,  tend  to  drop 
out,  and  the  molars  become  more  simplified.  Propachy- 
rucos  seems  to  represent  a  hold  over  of  the  most  primitive 
type  of  these.  The  Prohegetotherium  and  Hegetotherium 
have  retained  the  less  specialized  feet  and  less  advanced 
type  of  teeth,  while  Prosotherium  has  tended  to  the  develop- 
ment of  the  hopping  mode  of  locomotion,  which  is  attained 
in  Pachyrukhos  later.  There  thus  seem  to  be  two  series 
inside  of  this  family.  When  the  material  is  better  known, 
it  may  be  best  to  separate  the  two  series.  The  Eutrachy- 
theridae  have  retained  the  complexity  of  molars  united 
with  a  permanently  growing  incisor.  They  seem  also  to 
have  developed  into  a  series  of  comparatively  large  forms, 


N4 

£              f             E 

CO 
0 

60  THE  DESEADO  FORMATION  OF  PATAGONIA 

which,  as  they  have  advanced,  have  developed  a  bifurcated 
fold  on  the  inner  side  of  the  upper  molars,  which  in  its 
complete  development  makes  the  upper  molars  three-lobed, 
as  is  seen  in  the  typical  Typotherium,  representing  the 
end  of  the  series  up  in  the  Pampean  formation.  These 
relationships  may  be  expressed  graphically  as  in  fig.  26. 

ADAPTATIONS 

Most  striking  of  all  the  typothere  peculiarities,  is  the 
development  of  the  first  upper  and  lower  incisor  into  per- 
manently growing  teeth,  having  the  enamel  reduced  to  the 
anterior  side  only,  making  thus  a  self-sharpening  tooth 
similar  to  that  of  rodents.  Such  teeth  are  characteristic 
of  gnawing  forms  and  would  indicate  that  the  form  lived, 
in  at  least  a  considerable  part,  on  bark  and  twigs.  In  the 
eating  of  such  food  and  breaking  up  the  wood  cells  for  the 
contained  protoplasm  and  starch,  an  immense  amount 
of  chewring  is  involved,  followed  by  a  rapid  wear  of  the 
molars.  This  is  met,  as  is  characteristic  in  rodents  and 
grass  eaters,  by  the  development  of  first  high-crowned,  then 
permanently  growing  molars.  In  acquiring  the  perma- 
nently growing  tooth,  some  of  the  irregularities  of  the  crown 
are  lost,  others  which  are  deep-seated  enough  to  affect 
the  tooth  even  to  the  root  are  maintained,  so  that  especially 
the  external  and  internal  infoldings  become  a  persistent 
part  of  the  tooth,  having  been  impressed  into  the  dental 
papilla.  A  further  supplement  to  the  resistant  character 
of  the  teeth  is  seen  in  the  development,  in  the  most  ad- 
vanced types,  of  a  cement  layer  on  the  outside  of  the  molars, 
a  feature  apparently  also  a  part  of  permanently  growing 
roots. 

The  feet  are  generally  those  of  a  running  type,  but  a 
single  phylum  has  acquired  the  hopping  habit. 

The  above  features  seem  to  indicate  a  more  special 
adaptation  than  grass  feeding.  From  the  aspect  of  the 


ARCHAEOHYRAX  6l 

whole  Deseado  fauna,  we  would  seem  to  be  dealing  with 
the  inhabitants  of  an  arid  area,  where  bushes  have,  in  part 
at  least,  replaced  the  grass.  The  typotheres  seem  to  me 
to  represent  a  part  of  the  fauna  which  lived  by  gnawing 
the  bark  and  eating  the  twigs  and  leaves  of  bushes.  This 
does  not  preclude  the  eating  of  grass  also,  but  I  do  not 
see  how  they  would  have  developed  all  their  peculiarities 
by  eating  grass  alone.  The  rodents  are  of  such  insignifi- 
cant size  that  they  could  hardly  have  monopolized  this 
food  supply,  and  the  typotheres  seem  to  have  adjusted 
themselves  to,  and  occupied  the  place  of  rabbits  on  our 
western  plains;  but  went  even  farther  in  developing  in 
great  numbers  and  varieties. 

SYSTEMATIC  DESCRIPTIONS 
Archaeohyracidae  Ameghino 

This  family  is  differentiated  by  the  presence  of  enamel 
on  all  sides  of  the  first  incisor,  by  the  unreduced  condition 
of  the  lateral  incisors,  and  by  the  small  bulla  of  the  mas- 
toid.  These  are  primitive  features.  Ameghino  considered 
this  family  to  belong  to  the  hyracoids;  but,  as  explained 
earlier,  I  believe  them  to  be  true  Typotheria,  though  less 
specialized  than  the  other  families. 

Archaeohyrax  Ameghino 

Archaeohyrax  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  431. 

This  interesting  genus  is  known  by  a  complete  skull 
found  by  Ameghino  and  of  which  we  found  no  duplicates. 
I  insert  a  reproduction  of  the  side  view  of  the  skull,  and 
the  dentition  is  shown  in  fig.  24  a,  and  fig.  25  a.  The 
dental  formula  is  3,43.  Incisor  I  is  a  little  larger  than 
the  other  incisors.  Each  upper  molar  has  a  vertical  groove 
near  the  anterior  external  margin.  In  each  upper  premolar 
(after  the  first)  and  molar,  there  is  a  central  pit  surrounded 


62  THE  DESEADO  FORMATION  OF  PATAGONIA 

by  enamel,  which  is  opposite  the  internal  inflexion,  and 
in  a  young  individual,  is  presumably  connected  with  the 
fold.  In  the  same  way,  the  last  three  lower  premolars  and 
the  lower  molars  each  have  an  internal  pit,  adjacent  to 
the  external  inflexion.  With  advanced  age  all  the  teeth 
show  closed  roots,  another  primitive  feature.  In  spite 
of  the  closed  roots,  the  full  dentition,  and  the  enamel  on 
the  incisor;  and  on  account  of  the  deep  inflexions  and  the 
isolated  pits,  I  consider  this  genus  a  specialized  side  line, 
retaining  many  primitive  features,  and  expect  to  find  the 


Fig.  27.  Archaeohyrax  patagonicus,  after  Ameghino — natural  size. 

ancestor  of  the  typotheres  in  some  one  of  the  related  Casa- 
mayor  genera. 

Ameghino  described  three  species,  A .  patagonicus,  which 
we  have  figured,  and  which  has  a  length  of  84  mm.  from 
inc.  I  to  m.  3  in  both  the  upper  and  lower  dentitions;  A. 
propheticus,  of  the  same  size,  but  with  the  dental  series 
closed;  and  A.  concentricus  of  larger  size,  the  three  lower 
molars  having  a  length  of  38  mm. 

Plagiarthrus  Ameghino 

Plagiarthrus  Amcgh.,  1897,  Bol.  Inst.  Gcog.  Argen.,  t.  18,  p.  436. 

This  genus  is  known  only  by  the  lower  premolars  and 
molars,  which  are  permanently  growing  teeth,  composed 
of  two  subcylindrical  cylinders  almost  entirely  separated 


PLAGIARTHRUS  63 

by  the  external  and  internal  folds  which  almost  meet  in 
the  median  line.  On  the  outside,  each  tooth  is  coated  with 
a  layer  of  cement.  When  better  known  it  may  prove  that 
this  genus,  so  specialized  in  the  character  of  the  teeth, 
does  not  belong  in  this  family. 

Plagiarthrus  clivus  Ameghino 

P.  clivus  Amcgh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  436. 

This  species  is  represented  by  a  single  specimen  from 
the  Chico  del  Chubut,  west  of  Puerto  Visser,  which  pre- 
serves pm.  3  and  4  and  the  molars. 
The  characters  of  this,  the  type 
species,  are  those  of  the  genus.  Fig  2g  ^  lower  premolars  ?  and 
The  total  length  of  the  five  teeth  is  4  and  molars  '-3-^»tuiai  size. 
36  mm.,  and  fig.  28  shows  in  natural  size  the  various  in- 
dividual teeth. 

Hegetotheriidae  Ameghino 

This  family  includes  a  large  variety  of  forms  from  the 
formations  from  the  Deseado  up  to  the  Mt.  Hermosa,  but 
all  agree  in  having  the  first  upper  and  the  first  two  lower 
incisors  enlarged  into  strong  gnawing  teeth;  in  the  reduc- 
tion or  absence  of  in.  3,  the  canine,  and  premolar  I  of  the 
upper  and  lower  dentitions;  in  having  the  external  face  of 
the  upper  molars  not  inflexed ;  in  lower  molar  3  being  three- 
lobed;  and  in  the  bulla  being  inflated  and  hollow.  There 
are  in  the  family  two  series  of  forms,  at  least,  the  one  lead- 
ing to  the  running  Hegetotherium,  the  other  to  the  hopping 
Pachyrukhos,  and  the  very  little  known  form  Phanophilus 
which  may  fit  into  one  of  the  other  series  when  better 
known. 

In  the  Deseado  the  following  genera  are  assigned  to 
the  family. 

Prohegetotherium,  like  Hegetotherium,  except  that  the 
last  premolar  and  the  molars  have  a  vertical  furrow  near 
the  external  anterior  margin. 


64  THE  DESEADO  FORMATION  OF  PATAGONIA 

Prosotherium,  ]  °       »  uPPer  mc-  2  and  3  and  lower  inc. 


4  3 


3  vestigal,  upper  pms.  not  molariform,  molars  with  a  deep 
internal  fold. 

Propachyrucos,  3  l  4  3  ,  lower  jaw  only,  similar  to  Pa- 
chyrukhos  but  have  inc.  3,  the  canine,  and  pm.  I  present 
and  only  a  little  reduced. 

Phanophilus,  upper  molars  only,  but  peculiar  in  having 
a  strong  external  medial  column. 

Prohegetotherium  Ameghino 

Prohegetotherium  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  424. 

This  little  known  genus  is  characterized  by  the  upper 
molars  having  an  external  furrow  near  the  anterior  margin 
of  the  tooth.  Otherwise  it  is  similar  to  Hegetotherium. 
Ameghino  described  a  species  where  the  external  surface 
of  the  bones  was  sculptured  "like  reptiles."  I  do  not  see 
how,  with  the  arrangement  of  the  muscles  usual  to  mam- 
mals, the  sculpture  could  be  similar  to  that  of  reptiles,  and 
feel  that  this  is  due  to  conditions  of  weathering.  We  did 
not  find  this  species,  but  did  find  a  form  which  resembled 
it  in  general,  but  differed  in  being  smaller  and  with  the 
external  furrow  less  developed. 

Prohegetotherium  sculptum  Ameghino 

P.  sculptum  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  424. 

This  species  is  characterized  by  the  deep  external  fur- 
row on  the  upper  molars.  The  measure  given  is  34  mm. 
for  the  length  of  the  three  upper  molars. 

Prohegetotherium  shumwayi  sp.  nov. 
Founded  on  a  portion  of  the  right  maxilla,  carrying  pm. 
2  to  4  and  m.   I,  found  on  the  Chico  del 
Chubut,  west  of  Puerto  Visser,  by  Waldo 


Fig.  29.  H.   Shumwayi 

The  teeth  are  simple,  with  but  a  shallow 
external  furrow  near  the  anterior  margin  of  the  premolars 


PROSOTHERIUM  65 

and  molar.  A  film  of  cement  covers  each  tooth  and  extends 
to  the  top  of  the  crown.  The  form  is  smaller  than  P. 
sculptum. 

MEASUREMENTS 

Upper  premolar  3,  length  6  mm.,  width  3j  mm. 
Upper  premolar  4,  length  7  mm.,  width  3 5  mm. 
Upper  molar  I,  length  7  mm.,  width  35  mm. 

Prosotherium  Ameghino 

Prosotherium  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  426. 

In  founding  this  genus,  Ameghino  says  that  lower  pm. 
I  is  lacking,  but  our  specimens  show  it  present  as  a  vestige, 
and  also  show  no  trace  of  lower  inc.  3  against  which  Ame- 
ghino puts  a  question  mark,  making  the  formula  3043  as 
given  above.  The  upper  molars  are  similar  to  those  of 
Pachyrukhos  except  that  they  have  an  inner  fold  which 
has  been  lost  in  Pachyrukhos.  The  premolars  are  unlike 
the  molars.  Lower  molar  3  is  three-lobed.  The  descrip- 
tion of  the  skeleton  is  given  under  the  specific  description 
of  P.  garzoni,  and  this  shows  a  remarkable  resemblance  to 
the  skeleton  of  Pachyrukhos,  throughout,  so  that  I  have  no 
doubt  but  that  Prosotherium  is  the  ancestor  of  Pachyrukhos, 
the  changes  in  the  teeth  proceeding  in  the  line  of  simplifi- 
cation which  seems  to  be  general  in  this  order,  and  is  in 
general  characteristic  of  forms  in  which  the  teeth  become 
rootless. 

Ameghino  described  four  species,  P.  garzoni,  P.  trian- 
gulidens,  P.  robustum,  and  P.  quartum,  the  last  two  of 
which  differ  so  little  from  P.  triangulidens,  that  I  can  not 
consider  them  as  independent  species. 

Prosotherium  garzoni  Ameghino 

P.  garzoni,  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  426. 

This,  the  most  abundant  species  of  typotheres,  occurs 
in  our  collection  from  the  Chico  del  Chubut,  west  of  Puerto 


66  THE  DESEADO  FORMATION  OF  PATAGONIA 

Visser,  fifteen  times;  and  in  one  case  the  major  part  of  a 
skeleton  was  found,  consisting  of  the  skull  and  jaws,  verte- 
brae of  each  type,  ribs,  most  of  the  fore  limb,  the  pelvis 
and  a  hind  limb. 

The  animal  as  a  whole  is  smaller  than  P.  triangulidcus 
by  about  12%,  and  is  of  lighter  build.     The  skull  is  rela- 

ffl  tively  light  and  narrow, 
especially  in  the  rear, 
where  the  swollen  hollow 
capsules  of  the  squamo- 
sum  bones  come  within 
ten  millimeters  of  meet- 


Fig.  30.    Left  upper  dentition;  left  lower  dentition—  ing     medianly,     whereas, 
natural  size. 

in  other  species,  they  are 

twice  as  far  apart.  These  hollow  capsules  are  in  this  species 
the  most  marked,  and  in  this  genus  even  more  developed 
than  in  Pachyrukhos.  The  lachrymal  bone  is  larger  ex- 
ternally than  usual,  the  lachrymal  cluct  opening  about 
four  millimeters  in  front  of  the  margin  of  the  orbit,  and 
continuing  to  the  margin  by  an  open  groove.  In  P. 
triangulidens,  the  duct  is  inside  the  orbit.  The  heavy 
maxilla  makes  a  strong  process  for  the  zygomatic  arch, 
extending  fully  half  way  back  along  this  arch.  The  short, 
but  fairly  stout  jugale  has  but  a  short  contact  with  the 
maxilla. 

In  the  dentition,  the  premolar  and  'molar  teeth  are 
covered  with  a  thin  film  of  cement,  which  is  thicker  on  the 
outside  of  the  upper  teeth  and  on  the  inner  side  of  the 
lower  teeth.  On  the  opposite  sides  of  these  teeth  this 
film  is  so  thin  that  it  is  often  in  part 
worn  off. 

Specimen  3083  preserves  three  of 
the  deciduous  premolars.  Pm.  2  is  v 
simple  and  could  readily  be  taken  for  the  corresponding 
permanent  premolar,  except  that  it  is,  as  are  all  the  decidu- 
ous premolars,  rooted.  Deciduous  premolars  3  and  4,  on 


PROSOTHERIUM  GARZONI  67 

the  other  hand,  have  a  marked  inflexion  on  the  inner  side, 
giving  them  the  appearance  of  permanent  molars.  The 
series  measures  31  mm.  of  which  the  deciduous  premolars 
occupy  just  half. 

The  mandible  is  deep,  especially  the  posterior  portion; 
has  a  very  slender  coronoid  process;  and  a  slightly  rounded 
articular  condyle,  which  is  a  little  longer  than  wide,  so 


Fig.  32.     Left  mandible — natural  size. 

that  it  would  seem  to  allow  a  forward  and  backward  mo- 
tion of  the  lower  jaw. 

The  vertebrae  are  considerably  crushed,  but  have  in 
each  case  the  characteristics  of  the  corresponding  verte- 
bra of  Pachyrukhos. 

Of  the  humerus,  the  head  and  distal  ends  are  preserved, 
indicating  a  rather  long  and  slender  bone,  very  like  that  of 
Pachyrukhos.  About  three-fourths  of  the  ulna  is  present, 
and  it  is  also  long  and  slender,  with  a  wide  articular  facet 
for  the  radius,  which  is  entirely  separate  from  that  for  the 
humerus.  Two  metacarpals  show  the  same  elongation 
of  the  limb,  and  the  two  phalanges  preserved  indicate  a 
small  front  foot. 


68 


THE  DESEADO  FORMATION  OF  PATAGONIA 


Fig.  33.    Left  side  of  pelvis — natural  size. 


The  pelvis  is  elongated,  slender  and  lightly  built,  indicat- 
ing the  same  characteristics  in  the  whole  hind  limb.  The 
femur  has  a  small  rounded  head  on  a  well  marked  neck.  It  is 
excessively  long,  longer  than  that  of  Pachyrukhos,  and  also 


Fig.  35-    Patella- 
natural  size. 


Fig.  34.    Left   femur- 
natural  size. 


Fig.  36.  Tibia  and  fibula 
— natural  size. 


PROSOTHERIUM  GARZONI 


69 


Fig  37   Calcaneumi 


straighter.     It  is  further  distinguished  by  the  third  trochan- 

ter  being  swung  onto  the  back  side  of  the  bone.     The  tibia 

and  fibula  are  separate  throughout  their  en- 

tire length,  in  which  this  genus  is  in  strong 

contrast  to  Pachyrukhos,  where  these  two 

bones  are  fused,  both  distally  and  proximally. 
The  astragulus  is  also  quite  characteris- 

tic, the  trochlear  surface  being  entirely  on 

the  dorsal  surface,  and  the  condylar  ridges 

being  relatively  low  and  flat.     This  troch- 

lear  surface  is  far  from  being  symmetrical, 

the  inner  ridge  being  much  flatter  and  lower  uralsize- 

than  the  outer.  The  head  of  the  astragulus 
is  rounded,  on  a  long  neck,  and  directed 
obliquely  inward.  The  fibular  facet  for 
the  fibula  is  crescent-shaped  and  vertical 

Fig.  38.   Astragulus  from   CXCCpt      that      the      Small 
below  —  natural  size.  •         «  i      r  .,  i 

proximal  end  of  the  cres- 
cent flares  out.  The  outline  of  the  sus- 
tentacular  facet  is  that  of  an  acute  ovoid, 
and  is  situated  mostly  on  the  neck  of  this 
bone.  The  ectal  facet  is  roughly  rectan- 
gular in  outline,  strongly  concave,  and  is 
separated  from  the  sustentacular  facet 
by  a  deep  groove. 

The  calcaneum  is  of  moderate  size,  has 
a  narrow  fibular  facet,  a  broad  ectal  facet, 
and  a  moderately  large  sustentacular 
one.  The  facet  for  the  cuboid  is  slightly 
concave,  and  occupies  the  whole  of  the 
distal  and  of  the  calcaneum. 

The  metatarsals  are  moderately  long 
and    rather   heavy,   not   quite   as    long  Fig.  39.  Rightfoot—  natural 
and   slender   as   those   of  Pachyrukhos. 
The  phalanges  are  also  shorter  and  slightly  heavier  than 
those  of  Pachyrukhos.     We  found  four  proximal  and  four  of 


70  THE  DESEADO  FORMATION  OF  PATAGONIA 

the  second  series,  all  associated,  which  probably  indicates 
the  full  number  of  the  toes.  The  ungual  phalanges  are 
proximally  narrow  and  high,  then  expand  toward  the  tip, 
developing  into  marginal  expansions.  There  is  but  a  trace 
of  a  cleft  in  the  end  of  these  ungual  phalanges. 

MEASUREMENTS 

Skull,  greatest  length  99  mm. 

Upper  dentition,  length  inc.  I  to  m.  3  55  mm. 

Upper  dentition,  length  pm.  I  to  m.  3  31  mm. 

Upper  dentition,  incisor  I,  width  6\  mm. 

Upper  dentition,  molar  I,  length  6  mm. 

Upper  dentition,  molar,  width  4?  mm. 

Mandible,  greatest  length  82  mm. 

Lower  dentition,  length  inc.  I  to  m.  3  53  mm. 

Lower  dentition,  length  pm.  I  to  m.  3  32  mm. 

Lower  dentition,  molar  I,  length  6|  mm. 

Lower  dentition,  molar,  width  3  mm. 

Third  metacarpus,  greatest  length  28  mm. 

Pelvis,  length  front  to  back  83  mm. 

Femur,  greatest  length  (computed)  93  mm. 

Femur,  diameter  of  middle  of  shaft  9  mm. 

Tibia,  greatest  length  90  mm. 

Astragulus,  length  14  mm. 

Astragulus,  width  II  mm. 

Calcaneum,  length  25^  mm. 

Metatarsus  III,  length  32  mm. 

First  phalanx  of  digit  III,  length  12  mm. 

Ungual  palanx  of  digit  III,  length  9  mm. 

To  make  the  similarity  of  Prosotherium  with  Pachy- 
rukhos  clearer,  I  have  restored  Prosotherium,  figure  40, 
from  which  it  will  be  seen  that  this  genus  is  also  a  hopping 
form  with  a  plantigrade  hind  foot  and  a  semidigitigrade 
front  foot.  In  general  it  compares  very  closely  with  Pachy- 
rukhos,  but  the  limbs  are  shorter  and  the  grade  of  speciali- 
zation is  not  quite  as  high.  It  is,  however,  very  evidently 
the  ancestor  of  Pachyrukhos. 


PROSOTHERIUM  GARZONI 


72  THE  DESEADO  FORMATION  OF  PATAGONIA 

Prosotherium  triangulidens  Ameghino 

P.  triangulidens  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  427. 

P.  robustum,  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  427. 

P.  quartum  Amegh.,  1901,  Bol.  Acad.  Nac.  Cienc.  Cordoba,  t.  16,  p.  371. 

This  species  is  similar  to  P.  garzoni  except  for  size,  the 
forms  running  about  12%  larger,  and  being  heavier  built. 
In  this  same  line  the  upper  and  lower  molars  are  relatively 
wider  and  heavier.  The  top  of  the  skull  also  is  wider. 
I  have  drawn  carefully  the  skull  and  dentition  so  that  the 
detail  can  be  seen  from  the  figures.  Beside  triangulidens, 
Ameghino  described  P.  robustum,  which,  as  far  as  I  can 
see,  differs  only  in  being  about  5%  larger,  which  is  well 
within  individual  variation,  so  I  have  considered  it  as  a 
synonym.  The  same  is  the  case  with  P.  quartum,  which 
Ameghino  distinguishes  as  being  about  the  size  of  P. 
robustum,  and  having  lower  pm.  I  present.  The  latter 
character  we  found  also  characteristic  of  P.  garzoni,  so 
only  size  remains  and  I  do  not  consider  less  than  10% 
enough  by  itself  to  make  a  species. 

MEASUREMENTS 

Skull,  length  no     mm. 

Upper  dentition,  length  inc.  I  to  m.  3  57     mm. 

Upper  dentition,  length  pm.  I  to  m.  3  35     mm. 

Upper  dentition,  incisor  I,  width  8     mm. 

Upper  dentition,  molar  i,  width  4-!  mm. 

Six  specimens  from  Chico  del  Chubut 
Propachyrucos  Ameghino 

Propachyrucos  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.  t.  18,  p.  425. 

The  genus  is  based  on  lower  jaws,  in  which  the  characters 
of  the  premolars,  the  molars  and  the  first  two  incisors, 
resemble  those  of  Pachyrukhos;  but  in  this  genus  the  third 
incisor,  the  canine,  and  the  first  premolar  are  retained 
and  but  little  reduced.  Ameghino  has  described  two 
species,  P.  smithwoodwardi,  and  P.  aequilatus. 


PROSOTHERIUM    TRIANGULIDENS  73 


Fig.  41.  Top  view  of  the  skull,   palatal  view — natural  size. 


74  THE  DESEADO  FORMATION  OF  PATAGONIA 

Propachyrucos  smithwoodwardi  Ameghino 

P.  smithwoodwardi,  Amegh.,  1897,  Bol.  Inst.  Gcog.  Argen.,  t.  18,  p.  425. 

We  did  not  find  this 
species,  but  I  reproduce 
Ameghino's  figure  of  it, 
natural  size.  The  length 

Fig.  42.  P.  smithwoodwardi  after  Ameghino,  right    of    the    dentition    frOITl    mC. 
mandible — natural  size.  .  . 

I  to  m.  3  is  41  mm.,  height 
of  mandible  under  m.  i  is  12  mm. 

Propachyrucos  aequilatus  Ameghino 

P.  aequilatus,  Amegh.,  1901,  Bol.  Acad.  Nac.  Cit-nc.  Cordoba,  t.  16,  p.  371. 

This  species  is  based  on  the  anterior  lobe  of  each  lower 
molar,  being  longer  than  the  posterior.  In  size,  molars  I 
to  3  measure  24  mm.* 

Phanophilus  Ameghino 

Panophilus,  Amegh.,  1903,  Anal.  Soc.  Cienc.,  Argen.,  t.  56,  p.  202. 

This  genus  is  based  on  isolated  upper  molars,  charac- 
terized as  similar  to  Protypotherium,  but  having  a  pro- 
nounced median  vertical  column,  instead  of  a  groove  on 
the  external  face  of  the  upper  molars,  a  character  unique 
among  typotheres.  The  position  of  the  genus  with  this 
scant  information  is  uncertain.  One  species  is  described, 
P.  dorsatus. 

Phanophilus  dorsatus  Ameghino 

P.  dorsatus,  Amegh.,  loc.  cit.  p.  202. 

In  our  collection,  two  isolated  upper  molars  of  this  un- 
usual form  occur,  corresponding  in  size  and  pattern  to  the 
one  described  by  Ameghino.  The  external  column,  as 

*P.  crassus  has  been  described,  (loc.  cit.,  p.  425,)  based  on  pm.  2  and  3,  of 
larger  size  than  either  of  the  foregoing  but  I  do  not  think  that  the  genus  can 
be  determined  on  so  small  a  fragment. 


PHANOPHILUS  75 

seen  by  fig.  42,  is  narrow  and  high.  A  single 
tooth  measures  5!  mm.  from  front  to  back, 
and  3!  mm.  in  width. 

Specimen  3142  gen.  and  sp.  ? 
This  specimen  is  the  mandible  with  the  Vifwgof3mSareT- 
milk  dentition.  The  molars  present  suggest  naturalsize- 
Prosotherium  triangulidens,  but  inc.  3  and  the  canine  are 
present,  and  the  first  two  incisors  are  not  enlarged,  so  it 
would  seem  to  represent  a  genus  which  I  have  not  been 
able  to  identify.  Molar  I  is  bilobed  and  similar  to  that  of 
Prosotherium.  The  deciduous  premolars  are  all  present,  all 


Fig.  44.    Milk  dentition,  genus  and  species?  —  natural  size. 

rooted,  and  all  remarkable  for  their  great  antero-posterior 
elongation.  Roots  of  the  incisors  and  canine  are  present, 
that  of  the  canine  being  the  largest,  and  those  of  the  incisors 
being  about  equal  in  size.  This  would  suggest  such  a 
form  as  Proty  pother  ium,  were  this  genus  represented  in 
the  Deseado  beds. 

Interatheriidae 

The  family  is  characterized  by  the  incisors  not  being 
enlarged,  by  upper  and  lower  premolars  and  molars  being 
inflexed  on  both  the  inner  and  out  sides,  and  by  the  inflated 
mastoid  bulla  being  filled  with  cancellous  tissue.  The 
only  genus  referable  to  this  family,  from  the  Deseado 
beds,  is  Archaeophylus. 

Archaeophylus  Ameghino 

Archaeophylus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  423. 

The  genus  is  based  on  a  skull  which  preserved  most  of 
the  upper  dentition  except  the  incisors,  and  which  shows 
the  characteristics  of  the  family  in  their  inception. 


7  6  THE  DESK  ADO  FORMATION  OF  PATAGONIA 

Archaeophylus  patrius  Ameghino 

A.  patrius  Amegh.,  loc.  cit. 

We  found  no  specimen  of  this  inter- 
esting  type,  but  I  give  a  diagram  of 
Ameghino's  type,  which  shows  the  char- 


upper  dentition—  natural  size.  .      •  c      .-,  •  * 

actenstics   of   the   species    and    genus. 
The  length  of  the  premolar-molar  series  is  27  mm. 


Eutrachytheridae  Ameghino 

The  family  consists  of  larger  forms  than  the  other  fami- 
lies, and  is  characterized  by  the  upper  molars  having  the 
inflexion  bifurcated,  so  that  the  teeth  are  at  least  incipiently 
three-lobed.  I  would  place  in  the  family  the  genera, 
Eutrachytherus,  Argyrohyrax,  and  Isopoedrium. 

Eutrachytherus  Ameghino 

Trachytherus  Amegh.,  1889,  Act.  Acad.  Nac.  Cienc.  Cordoba,  t.  VI,  p.  918. 
Trachytherus  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  623. 
Eutrachytherus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  429. 

This  genus  was  first  called  Trachytherus,  and  when  this 
was  found  to  be  preoccupied,  changed  to  Eutrachytherus. 
Ameghino  gives  the  dental  formula  as  -2  °  ^ * ,  but  in  my 
specimen  which  is  a  comparatively  young  individual,  I 
find  a  small  alveolus  for  the  upper  canine,  which  modifies 
the  formula  to  \  [  ^ .  In  the  first  upper  dentition  found, 
incisors  2  and  3  were  represented  by  alveoli  only,  but  our 
specimen  shows  these  teeth,  and  we  find  that  they  have 
enamel  only  on  the  outer  face,  making  this  genus  more 
specialized  in  this  respect  than  any  of  the  other  typotheres. 
The  upper  molars  have  the  deep  inner  inflexion  bifurcated, 
which  makes  the  tooth  three-lobed,  a  character  which 
grows  more  marked  the  older  the  individual  is.  The  pre- 
maxillae  are  high  and  bring  the  snout  well  forward.  The 
nasals  are  lacking,  but  the  bounding  bones  show  them  to 


EUTRACHYTHERUS  77 

have  been  unusually  broad  and  flat.  The  maxilla  extends 
up  to  the  nasals,  and  bounds  the  lower  border  of  the  orbit, 
and  projects  backward  in  a  heavy  overhanging  zygomatic 
process.  The  lachrymal  bone  is  large  externally,  with  a 
large  but  low  lachrymal  tubercle  just  below  which  is 
found  the  lachrymal  duct,  opening  just  in  front  of  the 
margin  of  the  orbit.  The  frontals  are  short  and  wide, 
extending  outward  over  the  orbit  in  a  strong  postorbital 
process  which  bounds  half  of  the  rear  of  the  orbit.  The 
parietals,  meeting  medianly,  rise  in  a  strong  sagittal  crest. 
Unfortunately  the  back  part  of  the  cranium  is  lacking. 


Fig.  46.    E.  spegazzinianus — 1/2  natural  size. 


From  another  specimen,  which  contained  the  brain  cast, 
it  is  clear  that  the  bulla  was  much  inflated  and  hollow,  and 
that  there  was  an  inflation  in  the  upper  part  of  the  squa- 
mosum,  as  in  Prosotherium,  etc. 

One  specimen  with  the  facial  portion  badly  weathered, 
but  retaining  enough  to  identify  the  species  as  E.  spegaz- 
zinianus, preserved  the  brain  case,  so  that  it  could  be 
prepared  out. 

The  most  striking  feature  of  this  brain  is  its  relatively 
large  size,  E.  spegazzinianus  being  an  animal  about  the 
size  of  a  sheep,  and  the  brain  is  as  large  as  that  of  the 
sheep,  which  is  in  strong  contrast  to  what  would  be  ex- 
pected of  an  Oligocene  form.  Compared  with  the  herbiv- 


78  THE  DESEADO  FORMATION  OF  PATAGONIA 

orous  Oligocene  oreodont,  Eucrotaphus,  an  animal  of 
approximately  the  same  size,  this  brain  is  half  again  as 
large  in  every  way.  A  second  striking  feature  is  the  short 
compact  character  of  the  brain,  the  forebrain  extending 
only  a  short  distance  in  front  of  the  exit  of  the  optic  nerves, 
and  extending  backward  so  as  to  cover  most  all  of  the  cere- 
bellum. Thirdly,  the  cerebral  surface  is  considerably  con- 
voluted, comparable  to  the  convolution  of  a  pig's  brain. 
These  features  would  indicate  a  specialization  of  the  nerv- 
ous system,  approximating  that  of  the  skeleton,  and 
would  indicate  that  this  group  had  advanced  in  intelli- 
gence and  activity  beyond  the  grade  of  nervous  develop- 
ment which  is  apparent  in  the  contemporaries  of  the 
Typotheria. 

The  relatively  small  olfactory  lobes  are  entirely  beneath 
the  frontal  lobes  and  are  seen  only  on  the  side  view,  but 
as  there  is  a  large  hippocampal  lobe  behind  them,  it  would 
only  seem  proper  to  attribute  to  these  animals  a  wrell- 
developed  sense  of  smell.  The  frontal  lobes  are  unexpect- 
edly large,  and  are  not  clearly  bounded  off  from  the  parietal 
lobes.  The  occipital  lobes  are  also  well  developed  and  make 
a  large  portion  of  the  backward  extension  of  the  cerebrum. 
The  large  size  of  this  area,  together  with  the  fact  that  the 
optic  nerves  are  large,  indicates  a  good  visual  development. 
The  temporal  lobes  are  also  large  and  extend  well  down  on 
either  side.  And,  finally,  below  all  the  others,  come  the 
swollen  hippocampal  lobes  which  complete  this  large  cere- 
brum. 

The  cerebellum  is  small  having  neither  considerable 
width  or  height,  and  being  overlapped  by  the  cerebrum. 
The  optic  nerves  are  represented  by  large  projections  leav- 
ing the  twixt-brain  well  forward  under  the  forebrain. 
The  medulla  is  not  clearly  marked  except  to  show  that  it, 
too,  was  of  fair  size. 

Just  behind  the  hippocampal  lobes,  and  connecting  with 
the  cerebellum  appear  two  striking  projections.  These 


EUTRACHYTHERUS 


79 


Fig.  47.  Cast  of  the  brain;  A,  from  above;  B,  from  the  side — natural  size.  Cer,  cerebellum; 
F,  frontal  lobe;  H,  hippocampal  lobe;  Oct,  occipital  lobe;  Op,  optic  nerve;  T,  temporal  lobe;  x, 
cast  of  cavity  in  squamosal  bone;  Na,  case  of  interior  of  nasal  cavity. 

represent  the  two  large  cavities  in  the  upper  part  of  the 
squamosum  which  are  so  characteristic  of  typotheres. 
The  two  large  cavities  clearly  opened  into  the  brain  case 


80  THE  DESEADO  FORMATION  OF  PATAGONIA 

by  a  broad  connection  which  is  especially  wide  at  the  lower 
ends.  I  find  no  traces  of  a  connection  with  the  bulla  as 
described  by  Sinclair  for  Pachymkhos.  Further  down  are 
two  small  knobs  apparently  also  representing  cavities  in 
the  squamosum,  and  also  connected  with  the  brain  case. 
In  considering  the  brain  these  should  be  overlooked;  but 
they  doubtless  represent  some  nervous  function  to  which 
I  have  as  yet  no  clue. 

Ameghino  considered  that  Eutrachytherus  was  the  con- 
necting link  between  Archaeohyrax  and  Typotherium.  \ 
feel  that  this  genus  is  too  highly  specialized  to  be  a  con- 
necting form,  though  it  doubtless  belongs  to  the  series 
wThich  ends  in  Typotherium;  and  such  a  form  as  Argyro- 
hyrax  is  more  likely  to  be  the  really  ancestral  form. 

Two  species  are  described,  E.  spegazzinianus,  and  E. 
conturbatus,  which  is  about  15%  smaller.  Our  collection 
offers  a  third  species,  E.  grandis,  which  is  nearly  50%  larger 
than  the  first  named  species. 

Eutrachytherus  spegazzinianus  Ameghino 

Trachythcrus  spegazzinianus  Amegh.,  1889,  Act.  Acad.  Nac.  Cienc.  Cordoba, 

t.  VI,  p.  919. 

Trachytherus  spegazzinianus  Lydckkcr,  1894,  Anal.  Mus.  La  Plata,  pt.  3,  p.  2. 
Trachytherus  spegazzinianus  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p. 

622. 
Eutrachytherus  spegazzinianus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18, 

p.  428. 

This  species  was  founded  on  the  anterior  part  of  a  skull 
with  the  full  upper  dentition.  My  specimen  differs  from 
Ameghino's  in  having  a  tiny  alveolus  for  the  upper  canine, 
the  difference  being  due  to  my  specimen  being  younger. 

The  upper  dentition  is  very  characteristic.  Incisor  i 
is  a  powerful,  deep-set,  curved  gnawing  tooth,  with  a 
heavy  layer  of  enamel  on  the  anterior  face,  and  none  on 
the  other  sides;  and  is  moderately  beveled  in  the  rear  as  a 
result  of  wear.  The  second  and  third  incisors  are  much 
smaller,  each  having  enamel  on  the  outer  face  only,  and 


EUTRACHYTHERUS  SPEGAZZINIANUS 


8l 


with  a  marked  tendency  to  become  vestigal.  The  suture 
of  the  premaxilla  comes  to  the  base  of  inc.  3.  There  fol- 
lows a  short  diastema,  then  a  tiny  alveolus  for  the  canine, 
closely  followed  by  the  first  premolar  which  is  also  small. 
The  second  premolar  shows  no  inflexion.  Beginning  with 
the  third  premolar  there  is  a  strong  inner  inflexion,  which 
in  the  fourth  premolar  and  molars  is  bifurcated.  The 
molars  are  considerably  larger  than  the  premolars,  the 
second  being  the  largest  of  the  series.  With  each  succes- 
sive molar,  the  inflexion  is  wider,  so  that  in  m.  3  the  tooth 
is  divided  into  three  lobes  of  nearly  equal  size.  All  pre- 
molars and  molars  are  rootless,  curved,  and  set  so  deep  in 
the  jaw  that  they  almost  meet  in  the  median  line.  A  typi- 
cal molar  measures  50  mm.  in  length,  of  which  only  7-8 


Fig.  48.  E.  spegazzinianus ,  right  upper  dentition — natural  size. 

mm.   project  above  the  border  of  the  jaw.     All  the  back 
teeth  are  covered  with  a  thick  coating  of  cement. 

The  arrangement  of  the  teeth  of  the  lower  jaw  is  shown 
in  fig.  25  h.,  after  Ameghino.  The  first  and  second  incisors 
are  greatly  enlarged.  Incisor  3  is  lacking,  and  the  canine 
vestigal.  Pm.  I  is  small  and  single-lobed,  the  succeeding 
premolars  and  molars  being  large  and  divided  into  two  lobes 
by  a  deep  external,  and  a  shallow  internal  infolding. 

MEASUREMENTS 

Skull,  width  between  the  orbits  60  mm. 

Skull,  width  across  the  postorbital  processes  88  mm. 

Skull,  height  from  m.  2  to  top  of  frontal  77  mm' 

Skull,  width  of  palate  opposite  inc.  2 
Skull,  width  of  palate  opposite  m.  2 


Dentition, 

Dentition,  incisor  I  ant. — post. 
Dentition,  pm.  3 
Dentition,  m.  2 
6 


length  inc.  i  to  m.  3 
length  ii  mm. 
length  II  mm. 
length  22  mm. 


42  mm. 

62  mm. 
140  mm. 
width  16  mm. 
width  13  mm. 
width  16  mm. 


82 


THE  DESEADO  FORMATION  OF     PATAGONIA 


Eutrachytherus  conturbatus  Ameghino 

Trachytherus  conturbatus  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  623. 
Eutrachytherus  conturbatus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p. 
429. 

This  species  is  founded  on  upper  teeth,  which  are  said 
to  be  relatively  smaller  anteriorly,  and  actually  smaller 
throughout,  by  about  15%  than  are  those  of  the  preceding 
species.  Molar  I  measures  17  mm.  long  by  9  mm.  wide. 

Eutrachytherus  grandis  sp.  nov. 
This  species  is  based  on  upper  molars  I  and  2  of  the 

left  side,  from  the  Deseado  beds,  of  the  Chico  del  Chubut, 

west  of  Puerto  Visser. 
The  teeth  are  typically 
those  of  the  genus  and 
differ  only  from  other 
species  in  their  large 
size,  being  some  50% 
larger  than  the  corre- 
sponding teeth  of  E. 

spegazzinianus.     Each  is  covered  with  a  layer  of  fully  half 

a  millimeter  of  cement. 

MEASUREMENTS 

Upper  molar  I,  length  29  mm.,  width  21  mm. 
Upper  molar  2,  length  30^  mm.,  width  18  mm. 

Argyrohyrax  Ameghino 

Argyrohyrax  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  435. 

The  genus  is  distinguished  by  the  full  dentition  in  closed 
series,  and  by  the  upper  molars  having  a  deep  internal 
inflexion  which  is  bifurcated,  making  the  teeth  at  least 
incipiently  three-lobed.  Incisor  I  is  relatively  somewhat 
wider  than  in  the  preceding  genus.  It  seems  to  me  that 
it  is  from  such  a  genus  that  Typotherium  arose,  by  the 
reduction  of  the  lateral  incisors,  the  canine,  and  the  first 


Hi' 

Fig.  49.  E.  grandis,  molars  of  the  left  side — natural  size. 


ARGYROHYRAX  83 

two  premolars,  and  by  the  increase  of  the  bifurcated  in- 
ternal fold.  Three  species  have  been  described,  A.  pro- 
avus,  the  type  species,  A.  acutico status,  of  a  little  smaller 
size,  and  A.  proavunculus  of  still  smaller  size. 

Argyrohyrax  proavus  Ameghino 

A.  proavus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  436. 

This  species  occurs  three  times  in  the  Amherst  collec- 
tion. The  best  specimen  has  pm.  i,  3,  4,  and  m.  I  and  2 
of  the  upper  jaw.  The  species  is  characterized  by  a  nar- 
row furrow  near  the  anterior  external  margin  of  the  pre- 
molars and  molars;  and  by  pm.  3  and  4  and  the  molars 


Fig.  50.  Right  upper  dentition,  the  outline  teeth  after  Ameghino — 
natural  size. 

having  a  deep  internal  bifurcated  inflexion,  which  tends  to 
make  these  teeth  three-lobed. 

The  genus  is  known  only  by  the  upper  dentition,  and 
while  I  did  not  find  any  associated  lower  teeth,  I  believe 
that  some  one  of  the  genera  known  only  by  the  lower  den- 
tition, like  Plagiarthrus,  is  that  lower  dentition. 

MEASUREMENTS 

Upper  dentition,  length  inc.  I  to  m.  3  (@  Ameghino)  71  mm. 

premolar  I,  length  7  mm.,  width  4  mm. 

premolar  3,  length  7  mm.,  width  6  mm. 

premolar  4,  length  8  mm.,  width  6  mm. 

molar  I,       length  8  mm.,  width  6£  mm. 

Argyrohyrax  praavunculus  Ameghino 

A.  proavunculus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  436. 

The  species  is  simply  said  to  be  much  smaller  than  the 
preceding,  which,  by  the  measurements,  would  figure  out 
about  27%.  The  measurements  given  are  pm.  I  to  m.  3, 
33  mm. 


84  THE  DESEADO  FORMATION  OF  PATAGONIA 

Argyrohyrax  acuticostatus  Ameghino 

A.  acuticostatus  Amegh.  1901,  Bol.  Acad.  Nac.  Cienc.  Cordoba,  t.  16,  p.  361. 

This  species  is  described  as  differing  from  A.  proavus 
in  being  somewhat  smaller,  but  I  find  it  about  the  same 
size.  The  specific  character  is  in  the  teeth  being  more 
compressed,  and  in  the  anterior  vertical  margin  of  the 
upper  molars  being  developed  in  the  form  of  a  very  salient 
crest. 

Isoproedrium  Ameghino 

Proedrium  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  623. 
Proedrium  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  431. 
Isoproedrium,  Amegh,  1903,  Anal.  Soc.  Cient.  Argen.,  t.  56,  p.  18. 

This  genus  is  based  on  a  toothless  mandibular  sym- 
physis  of  large  size,  on  which  the  second  incisor  is  indicated 
as  larger  than  the  first.  We  found  one  lower  jaw,  which, 
though  imperfect,  confirms  the  above  as  a  genus  and  adds 
the  following  for  generic  characters;  premolars  with  a 
shallow  inflexion  on  the  inner  and  outer  sides,  the  molars 
with  a  shallow  inner,  and  a  narrow  deep  outer  inflexion, 
heavy  layer  of  cement  on  the  premolars  and  molars, 
enamel  reduced  on  the  anterior  internal,  and  the  posterior 
internal  corners  of  at  least  the  premolars. 

Isoproedrium  solitarium  Ameghino 
loc.  cit.  above. 

I  have  assigned  the  specimen  shown  in  fig.  51  to  this 
species.  Alveoli  of  the  first  and  second  incisors  show  inc. 


,    7,     r-       " 

Fig.  51.    Right  mandible,  dotted  line  indicated  alveolus — natural  size. 

2  considerably  larger  than  inc.  I.     About  the  third  incisor 
and  the  canine  my  specimen  shows  nothing,  being  broken 


ISOPROEDRIUM  85 

down  in  that  region.  Pm.  I  is  represented  by  a  moder- 
ately large  alveolus,  10  mm.  long.  Pm.  2  is  13  mm.  long 
by  10  mm.  wide,  and  slightly  constricted  medianly  as  far 
as  the  enamel  is  concerned,  the  furrow  in  either  side  being 
filled  with  cement.  Pm.  3  is  18  mm.  long  by  12  wide  and 
similar.  There  is  only  an  alveolus  for  pm.  4,  which  is 
23  mm.  long.  M.  I  is  incomplete,  but  was  about  23  mm. 
long  by  10%  mm.  wide  and  is  distinguished  by  the  deep 
outer  inflexion.  Each  tooth  present  is  covered  with  a 
heavy  layer  of  enamel  nearly  a  millimeter  thick;  and  each 
of  the  teeth  is  unique  in  that  the  enamel  is  wanting  on 
the  anterior  internal  and  the  posterior  internal  corners  of 
the  teeth. 


CHAPTER  VI 

TOXODONTIA 

THE  toxodonts  of  the  Deseado  are  much  more  varied 
than  those  of  the  Santa  Cruz,  and  less  so  than  those  of 
the  Casamayor;  the  teeth  less  hypsodont  than  in  the  Santa 
Cruz,  and  more  hypsodont  than  in  the  Casamayor;  are 
smaller  than  those  of  the  Santa  Cruz,  and  larger  than  those 
from  the  Casamayor.  It  is  a  group  of  heavy,  short-limbed, 
nonadaptive  animals,  which,  as  time  and  competition  pro- 
gressed, gradually  diminished  in  numbers  and  variety. 

The  ancestral  type  must  be  sought  in  some  such  a  form 
as  Henricosbornia,  where  the  upper  molars  are  brachydont, 
have  the  four  primary  cusps  distinct,  and  the  connecting 
crests  of  small  size,  and  a  cingulum  moderately  developed 
on  the  front  and  rear  sides.  Progress  is  in  the  line  of  en- 
larging the  crests,  so  that,  in  the  later  forms,  the  two  exter- 
nal cusps  are  united  to  make  a  wall;  and  the  anterior 
external  and  the  anterior  internal  cusps  are  united  into  the 
large  anterior  lobe;  while  the  posterior  external  and  the 
posterior  internal  cusps  unite  to  make  the  posterior  lobe. 
These  may  remain  relatively  simple  as  in  Rhynchippidae* ; 
or  with  this  simple  arrangement  of  the  cusps,  the  cingulum 
may  be  developed  into  a  platform  around  the  anterior, 
inner,  and  posterior  sides  of  the  molars,  as  in  the  Isotem- 
nidae;  or,  with  relatively  simple  molars,  the  incisors  may 
be  specialized  into  caniniform-like  teeth  as  in  the  Leon- 
tiniidae;  or  secondary  processes  (or  cristae)  may  develop 
from  the  wall,  making  the  complicated  teeth  characteristic 
of  Nesodontidae. 

*  I  have  abandoned  the  family  term  Notohippidae,  as  the  genus  used  as  a 
basis  is  very  little  known,  and  the  forms  Ameghino  assigns  to  the  family,  to 
my  mind,  mostly  belong  with  the  Nesodontidae. 


TOXODONT  TEETH 


WJ**  3 


For  convenience  in  discussing  the  modifications  of  the 
toxodont  tooth,  I  have,  throughout,  used  the  nomenclature 
illustrated  in  fig.  52,  taking  one  of  the  most  complicated  to 
-*  ;.  show  the  ultimate  development.  In 

the  upper  tooth  there  is,  first,  the 
external  wall,  from  which  springs 
the  anterior  lobe,  always  the  larger 
lobe,  and  composed  of  the  protocone 
and  paracone  of  Osborn.  In  the 
rear  is  a  smaller  narrower  pos- 
terior lobe,  composed  of  the  hy- 
pocone,  the  metacone,  and  the 
metaconule  of  Osborn.  Between 
these  is  a  large  basin,  which  may 
be  subdivided  by  two  cristae  into 
secondary  bays,  referred  to  as  bays 
I,  2  and  3,  while  the  cristae  are  in 
the  same  way  referred  to  as  cristae 
I  and  2.  In  some  genera,  the  cristae 
are  entirely  wanting,  in  others  in- 
cipient. When  fully  developed,  they 
are  most  marked  in  young  individ- 
uals and,  as  the  tooth  is  worn,  appear  progressively  shorter. 
Behind  the  posterior  lobe,  there  is  a  variable  bay,  number  4 
which  is  bounded  behind  by  crista  3,  which  is  apparently 
a  development  of  the  posterior  cingulum.  This  last  crista 
and  bay  may  or  may  not  be  present. 

The  lower  molars  of  toxodonts  are  all  on  the  same  plan, 
each  tooth  being  composed  of  two  crescents,  the  anterior 
and  posterior.  The  ends  of  these  crescents  are  referred  to 
as  the  anterior,  median  and  posterior  horns.  The  bay  in 
the  anterior  crescent  is  simple  and  usually  disappears  with 
the  wear  of  the  tooth  without  making  a  pit.  In  the  centre 
of  the  posterior  crescent  is  the  pillar  or  posterior  tubercle 
which  Scott  has  found  to  be  characteristic  of  these  South 
American  Ungulates.  It  is,  to  my  mind,  the  same  as  the 


88  THE  DESEADO  FORMATION  OF  PATAGONIA 

mesostylid  of  the  Fayum  hyracoids.  Between  the  pillar 
and  the  median  horn,  I  find  a  narrow  vertical  ridge,  which 
I  have  termed  the  septum;  and  which  tends  to  unite  with 
the  pillar  inclosing  a  small  bay,  usually  seen  in  worn  teeth 
as  a  pit.  The  bay  between  the  septum  and  the  median 
horn  is  designated  bay  2,  and  this  quite  generally  appears 
in  a  worn  tooth  as  a  pit  (2).  The  bay  between  the  septum 
and  pillar  is  designated  bay  3,  and  is  usually  seen  as  a  tiny 
pit,  which  however  does  not  extend  as  deep  into  the  crown 
as  the  other  pits  and  is  usually  lost  when  the  tooth  is  about 
half  worn  off.  The  bay  between  the  pillar  and  the  posterior 
horn  is  numbered  4,  and  is  usually  open,  though  in  a  worn 
tooth  it  also  may  appear  as  a  pit.  The  effect  of  wear  is 
shown  by  comparing  B  and  C  in  fig.  52,  the  latter  being 
the  same  tooth  sectioned  a  little  below  the  middle.  I  find 
in  studying  a  lower  molar  of  Coresodon  that  bay  3  becomes 
a  pit  after  some  6  mm.  are  worn  off,  while  bays  2  and  4 
remain  open  until  some  10  mm.  are  worn  off  when  they 
also  become  pits.  Pit  3  will  disappear  when  12  mm.  are 
worn  off,  but  pits  2  and  4  run  to  the  base  of  the  crown. 

The  various  genera  of  the  Toxodontia  in  the  Deseado 
I  would  divide  into  four  families  as  follows : 

Rhynchippidae :  molars  brachydont,  secondary  cristae 
lacking  or  little  developed,  none  of  the  incisors  caniniform, 
limbs  slender,  feet  digitigrade,  digits  3-3. 

Leontinidae:  molars  brachydont,  secondary  cristae 
lacking  or  little  developed,  upper  inc.  2  and  lower  inc.  3 
developed  into  caniniform  teeth,  limbs  heavy,  feet  digiti- 
grade, digits  3—3  (according  to  Gaudry). 

Isotemnidae :  molars  brachydont,  secondary  cristae 
more  or  less  developed,  crowns  contracted  at  the  top,  con- 
gulum  more  or  less  developed  into  a  platform,  skeleton 
unknown. 

Nesodontidae :  molars  hypsodont,  secondary  cristae 
highly  developed,  upper  inc.  2  and  lower  inc.  3  caniniform, 
limbs  heavy,  feet  digitigrade,  digits  3-3. 


TOXODONT  CLASSIFICATION  89 

Rhynchippidae 

This  family  name  is  used  for  the  three  genera  Rhyn- 
chippus, Morphippus,  and  Eurygeniops,  which  made  up  a 
part  of  Ameghino's  family,  Notohippidae.  These  forms  I 
find  much  simpler  than  Coresodon,  Interhippus,  Stilhippus, 
and  Nesohippus,  which,  by  their  molars,  should  be  asso- 
ciated with  Nesodontidae,  unless  it  should  prove  that  they 
did  not  have  the  incisors  enlarged  to  caniniform  teeth,  in 
which  case  another  disposition  will  have  to  be  made  of 
them.  Ameghino  places  the  Rhynchippidae  among  his 
Hippoidea,  leading  to  horses,  but  we  found  a  nearly  com- 
plete skeleton  of  Rhynchippus  equinus  which  in  all  particu- 
lars is  typically  toxodont.  In  the  Deseado  we  found 
fourteen  specimens  belonging  to  this  family,  and  strangely 
enough  they  were  all  Rhynchippus,  and  all  of  the  species 
R.  equinus. 

This  family  is  distinguished  by  the  brachydont,  or 
nearly  brachydont,  molar  teeth,  being  relatively  simple, 
and  the  secondary  cristae  not  being  developed.  The  large 
basin  in  the  upper  premolars  and  molars  is,  therefore,  not 
subdivided,  but  is  deep,  and  rather  narrow,  usually  ap- 
pearing as  an  oblique  pit  in  the  centre  of  the  crown.  There 
is  no  enlargement  of  the  incisors  to  make  caniniform  teeth. 
Both  the  upper  incisors  and  the  canine  have  in  the  crown 
a  longitudinal  groove,  which  on  wear  becomes  a  pit,  and 
being  shallow  may  disappear  entirely.  The  lower  teeth 
are  those  typical  of  all  toxodonts.  The  feet  are  tridactyl, 
and  compact. 

The  following  three  genera  may  be  distinguished : 

RHYNCHIPPUS  MORPHIPPUS  EURYGENIOPS 

3143  3143  3143 

Formula  TTTT  TTTT  TTTT 

Skull  moderately  long  muzzle    short      muzzle,      with     short     heavy      muzzle, 

slight  constriction  be-       with  marked  constric- 
hind  canines  tion  behind  canines 

Upper  incisors  groove  or  pit  groove  or  pit  groove  or  pit 


90  THE  DESEADO  FORMATION  OF  PATAGNOIA 

RHYNCHIPPUS  MORPHIPPUS  EURYGENIOPS 

Lower  incisors  cingulum  on  the  inner     no  cingulum  no  cingulum 

face 

Upper  premolars       cingulum    on    ant.    int.  cingulum    on    ant.    int.  cingulum    on    ant.    int. 
corner  corner  corner 

Upper  molars  basin  deep  basin  shallow  basin  deep,  with  incipi- 

ent secondary  bays 

Lower  molars  4  bays  bays  i  and  2  only  bays  i  and  2  only 


Rhynchippus  Ameghino 

Rhynchippus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  462. 

The  teeth  of  both  jaws  are  rooted,  but  tend  to  be  hypso- 
dont.  The  elongated  incisors  of  the  upper  series  are  char- 
acterized by  the  presence  of  a  longitudinal  furrow  in  the 
top  of  each  tooth,  which,  with  wear,  becomes  a  pit,  and, 
as  it  is  shallow,  disappears  in  old  individuals.  This  is  the 
only  suggestion  of  a  horse  character  in  the  genus,  but  the 
pit  in  a  horse's  incisor  is  a  late  development,  and  here  it  is 
also  probably  a  specialization  due  to  eating  grass.  Incisor 
I  is  the  largest  and  they  decrease  in  size  toward  either  side. 
The  canine  is  small,  and  is  also  marked  by  having  a  furrow 
in  the  crown,  but  in  this  case  it  is  transverse  to  the  long 
axis  of  the  jaw. 

The  premolars  are  peculiar  in  having  on  the  anterior 
internal  corner  a  highly  developed  cingulum,  which  so 
builds  out  the  tooth  that  it  is  usually  wide  and  is  rectangu- 
lar in  outline.  As  this  cingulum  rises,  it  incloses  a  bay  on 
the  ant.  int.  corner  of  the  tooth,  which,  with  wear,  becomes 
first  a  bay,  then  a  pit,  and  lastly  may  disappear  entirely 
in  old  age.  On  each  premolar  the  anterior  and  posterior 
lobes  are  developed,  inclosing  between  them  an  elongated 
basin,  which  with  wear  becomes  a  long  narrow  pit.  On 
the  molars,  the  cingulum  on  the  ant.  int.  corner  is  wanting 
entirely.  The  external  anterior  corner  of  the  tooth,  how- 
ever, is  prolonged,  so  that  the  crown  has  a  rhomboidal  out- 
line. The  crown  is  made  up  in  the  typical  manner  of  the 
wall,  the  anterior,  and  the  posterior  lobes,  which  inclose 


RHYNCHIPPUS  91 

between  them  an  elongated  basin,  which,  as  in  the  pre- 
molars,  becomes,  on  wear,  a  pit  extending  obliquely  across 
the  tooth. 

The  lower  incisors  have  no  furrows  in  the  crowns,  but 
in  this  genus  there  is  a  small  cingulum  on  the  inner  side 
just  above  the  base  of  the  enamel.  The  lower  canine  is 
incisiform,  and  also  has  the  basal  cingulum.  Each  of  the 
premolars  has,  on  the  external  side,  a  median  vertical 
groove,  beginning  at  the  base  of  the  enamel,  and  widening 
toward  the  top.  This  is  progressive  if  less  marked  from 
pm.  i  to  pm.  4.  The  premolars  and  molars  consist  essen- 
tially of  two  crescents,  the  shorter  anterior,  and  the  pos- 
terior which  is  about  twice  as  long  as  the  anterior.  The 
details  are  as  described  on  page  96,  and  seen  in  figure  55. 

The  skull  is  of  moderate  height,  nearly  flat  on  top  with 
wide  zygomatic  arches.  The  sagittal  crest  is  moderately 
high,  and  slightly  convex  in  the  antero-posterior  direction. 
The  occipital  region  is  overhanging  and  topped  by  short 
lambdoidal  crests,  which,  extending  to  either  side,  unite 
with  the  zygomatic  arches.  The  nasals  are  large,  roughly 
rectangular,  and  slightly  constricted  just  in  front  of  the 
middle.  The  f rentals  are  short,  and  project  over  the  orbits 
in  strong  processes.  The  maxilla  is  large,  bounding  the 
front  of  the  orbit,  and  extending  backward  in  a  strong 
zygomatic  process  which  makes  nearly  half  of  the  arch. 
The  jugal,  while  stout,  is  short,  and  reaches  from  the  long 
zygomatic  process  of  the  maxilla  to  the  short  one  of  the 
squamosum.  The  lachrymal  bone  is  tiny,  with  a  low  tu- 
bercle, just  below  which  is  situated  the  lachrymal  duct, 
just  on  the  margin  of  the  orbit.  Just  behind  the  zygomatic 
arch,  the  squamosum  is  inflated  and  contains  a  large  hol- 
low chamber,  as  is  typical  among  toxodonts.  The  mastoid 
bullae,  while  relatively  small,  are  swollen  into  a  globular 
form,  and  have  a  large  hollow  chamber. '  The  palate  ex- 
tends back  to  just  behind  the  last  molar,  a  feature  distin- 
guishing this  genus  from  Morphippus. 


92  THE  DESEADO  FORMATION  OF  PATAGONIA 

Of  the  vertebral  column,  twenty-six  vertebra  are  pre- 
served (a  few  being  represented  by  neural  arches  only). 
The  atlas  and  axis  are  unknown.  Five  cervicals  are  pres- 
ent, each  with  a  short,  slightly  opisthocoelus  centrum,  and 
with  low  weak  spines.  The  foramena  for  the  vertebra  artery 
are  usually  large.  Cervical  3  has  a  rather  slender  trans- 
verse process,  projecting  down — and  backward.  On  cer- 
vicals 4,  5  and  6,  these  lateral  processes  are  enlarged  into 
broad  lamellae,  which  reach  their  maximum  of  size  on  the 
sixth.  Cervical  7  has  no  lamella,  simply  a  slender  trans- 
verse process.  These  transverse  processes  are  strikingly 
like  those  of  Nesodon.  The  thoracic  vertebrae  (of  which 
I  have  complete  or  in  parts  15)  have  moderately  high  spines, 
which  resemble  those  of  Adinotherium,  not  only  in  the  gen- 
eral build,  but  also  in  the  presence  of  a  foramen  for  the 
exit  of  spinal  nerves  through  each  neural  arch.  These 
foramena  can  not  be  referred  to  as  adaptations,  but  are 
special  features  indicating  close  relationship  with  the  Neso- 
dontidae.  Six  lumbar  vertebra  are  present,  each  having 
broad  depressed  centra,  and  short  wide  spines.  The  rest 
of  the  column  is  unknown. 

The  distal  portion  of  the  humerus  is  preserved,  showing 
the  trochlea  to  be  relatively  narrow,  with  a  prominent 
internal  phlange  for  the  ulna.  The  epicondyles  are  both 
small.  The  supratrochlear  fossa  is  moderately  deep,  the 
anconeal  fossa  very  deep,  a  large  perforation  connecting 
the  two.  Of  the  ulna,  only  the  distal  end  is  preserved,  and 
it  is  marked  by  a  prominent  styloid  process,  ending  in  the 
facet  for  the  pyramidal,  this  facet  continuing  uninter- 
ruptedly into  that  for  the  pisiform.  The  two  ends  of  the 
radius  are  preserved  but  its  length  can  only  be  conjectured. 
The  proximal  end  has  a  large  facet  for  the  humerus;  the 
distal  end  two  facets,  for  the  scaphoid  and  luna  respec- 
tively, the  two  being  almost  continuous,  except  as  the 
outline  of  the  shallow  depressions  is  constricted  near  the 
middle. 


RHYNCHIPPUS  93 

The  carpus  is  preserved  in  toto  and  is  decidedly  weak 
for  an  animal  of  this  size,  though  no  more  so  than  is  the 
case  of  Nesodon  and  Adinotherium,  with  which  forms  the 
arrangement  of  the  bones  agrees  in  almost  every  detail. 
The  scaphoid  has  a  broad  facet  on  the  upper  side  for  the 
radius,  on  the  ulna  side  a  narrow  band-like  facet  for  the 
luna,  and  distally  facets  for  the  trapezoid  and  the  magnum, 
none  for  the  trapezium.  The  luna  is  a  larger  bone  with  a 
broad  radial  facet  on  the  upper  side,  a  narrow  facet  for  the 
scaphoid  on  the  radial  side,  a  larger  one  for  the  pyramidal 
on  the  ulnal  side,  and  two  broad  facets  for  the  magnum 
and  unciform  on  the  lower  side.  The  pyramidal  is  a  low, 
flattened  bone,  with  a  cup-like  facet  for  the  ulna  on  the 
upper  surface,  an  elongated  flat  facet  for  the  pisiform  on 
the  palmar  surface,  and  below  a  broad  facet  occupying  the 
entire  lower  side  for  the  unciform.  The  pisiform  is  shaped 
like  a  tiny  calcaneum,  and,  beside  the  facet  for  the  pyra- 
midal, has  a  broad  contact  on  the  styliform  process  of  the 
ulna.  The  trapezium  is  a  flattened  nodular  bone,  resting 
against  the  side  of  the  upper  end  of  Me.  II,  for  which  it  has 
a  flattened  contact  surface,  but  it  does  not  properly  artic- 
ulate with  any  of  the  carpals.  The  trapezoid  is  a  small 
bone,  cuboidal  in  shape,  with  the  proximal  facet  for  the 
scaphoid  rounded,  and  with  a  narrow  facet  for  the  sup- 
port of  Me.  II  on  the  distal  end.  The  magnum  is  a  larger 
bone,  articulating  proximally  with  the  scaphoid  and  luna, 
on  the  ulnal  side  with  the  unciform  and  distally  supporting 
Me.  III.  The  unciform  is  the  largest  of  the  carpal  bones, 
articulates  proximally  on  the  luna  and  pyramidal,  on  the 
radial  side  with  the  magnum,  and  distally  carries  Me.  IV, 
while  on  the  ulnal  side  there  is  a  facet  for  the  modular  ves- 
tige of  Me.  V. 

The  metacarpals  are  longer  than  those  of  Adinotherium, 
and  are  much  more  closely  pressed  together,  making  a 
narrower,  firmer  foot.  Three  metacarpals  are  present 
(beside  the  modular  vestige  of  Me  V.).  Me.  II  and  Me.  IV 


94  THE  DESEADO  FORMATION  OF  PATAGONIA 

are  slightly  shorter  than  Me.  Ill,  but  not  materially  weaker, 
so  that  all  three  would  reach  the  ground  when  the  animal 
was  standing.  Though  closely  packed,  the  metacarpals 
are  not  grown  together  at  any  point.  Distally  each  has 
a  narrow  trochlea,  which  carries  a  median  crest  on  the 
palmar  side  only.  Under  the  distal  end  of  each  metacarpal, 
there  is  a  pair  of  small  sesamoid  bones. 

All  the  phalanges  are  very  short  and  weak,  with  the 
articular  surfaces  cut  under  obliquely,  suggesting  that  the 
toes  are  bent  upward.  Distally  each  toe  ends  in  a  slender 
cleft  ungual  phalanx,  suggesting  a  claw-like  hoof.  Rhyn- 
chippus  clearly  walked  in  a  semidigitigrade  manner,  the 
weight  coming  principally  on  the  metapodials,  the  foot 
as  a  whole  resembling  that  of  a  dog. 

The  pelvis  is  unidentified.  Though  the  bones  are  of 
about  the  same  weight,  the  hind  limb  is  longer  than  that 
of  Adinotherium.  The  femur  has  a  rounded  head  on  a 
short  but  distinct  neck,  with  the  pit  for  the  round  ligament 
on  the  posterior  margin  of  the  head.  The  narrow  digital 
fossa  is  deep.  The  greater  trochanter  is  rugose  and  strong, 
but  does  not  rise  quite  to  the  height  of  the  head.  The 
lesser  trochanter  makes  a  strong  shelf-like  process  well 
below  the  head,  while  the  third  trochanter  is  a  prominent 
process  about  the  middle  of  the  shaft,  on  the  posterior  side. 
The  shaft  is  broad  and  flattened  above,  but  narrows  and 
becomes  circular  in  section  below.  The  condyles  are  rela- 
tively small,  the  inner  being  the  smaller  and  more  convex, 
while  the  outer  is  broader  and  less  convex. 

The  tibia  and  fibula  are  a  little  longer  than  the  femur, 
fused  proximally,  free  distally,  as  in  toxodonts.  The  prox- 
imal end  of  the  tibia  is  too  weathered  to  permit  detailed 
description.  However  the  upper  end  is  wide  and  flattened 
from  front  to  back.  Distally  the  bone  narrows  until  the 
lower  part  of  the  shaft  is  circular  in  section,  the  distal  end 
enlarging  again  in  the  neighborhood  of  the  articulation. 
The  fibula  has  a  broad  facet  for  the  inner  side  of  the  astra- 


RHYNCHIPPUS  95 

gulus,  and  on  the  distal  end  a  flattened  slightly  concave 
facet  for  the  calcaneum. 

The  calcaneum  is  longer  than  in  Nesodontidae.  It  is, 
however,  heavy  and  stout,  the  tuber  broadening  slightly 
toward  the  free  end,  on  the  plantar  side  of  which  there  is  a 
tendinous  sulcus  as  in  Nesodon.  The  fibular  facet  is  wide, 
rectangular,  and  convex.  Of  the  astragular  facets,  the 
sustentacular  extends  well  back  onto  the  tuber,  and  the 
ectal  is  the  usual  ovoid  surface.  Distally  there  is  a  broad 
slightly  concave  facet  for  the  cuboid,  and  external  to  this 
a  narrow  surface  for  contact  on  the  navicular.  Except  in 
length,  this  bone  is  very  like  that  of  Adinotherium.  The 
astragulus  and  rest  of  the  tarsal  bones  are  wanting.  Parts 
of  the  metatarsals  and  a  phalanx  indicate  that  the  hind 
foot  is  of  the  same  tridactyl  type  as  the  front,  differing 
only  in  that  the  median  digit  seems  to  be  relatively  a  little 
heavier. 

Ameghino  described  three  species  of  Rhynchippus,  R. 
equinus,  R.  pumulis,  and  R.  medianus. 

Rhynchippus  equinus  Ameghino 

R.  equinus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  463. 

This  species  is  the  dominant  one  in  the  Deseado  from 
the  Chico  del  Chubut,  west  of  Puerto  Pisser,  no  less  than 
fourteen  individuals  being  represented  in  our  collection, 
three  by  skulls,  and  one  by  the  major  part  of  a  skeleton 
which  was  found  associated  with  the  skull  of  Leontinia, 
but  was  determined  as  belonging  to  this  species,  by  the 
duplication  of  the  radius  with  a  specimen  having  the  radius 
and  lower  jaws  associated.  The  description  of  the  generic 
characters  is  largely  based  on  this  skeleton.  The  three 
species  are  differentiated  largely  by  their  size,  R.  equinus 
being  the  largest,  but  as  compared  with  R.  pumulis  it  is 
not  only  larger  but  much  heavier  built. 

The  skull  has  been  described  under  the  generic  discus- 
sion. In  young  individuals,  the  furrow  in  the  incisors  and 


96 


THE  DESEADO  FORMATION  OF  PATAGONIA 


canine  is  marked  as  a  groove,  later  as  a  pit,  and  still  later 
is  lacking  altogether,  as  is  the  case  in  the  specimen  figured, 
for  all  three  of  my  more  complete  specimens  are  old  indi- 
viduals, as  is  also  Ameghino's  type.  All  the  incisors  show 


Fig.  53.    Dorsal  view  of  skull — 1/2  natural  size. 


the  cingulum  near  the  base  of  the  enamel.  On  account  of 
the  development  of  the  cingulum  on  the  inner  anterior  cor- 
ner of  the  premolars,  these  teeth  are  broadened  out  and 
overhang  the  palate  in  a  marked  degree,  and  are  also  much 
wider  than  long.  Molar  I  is  intermediate  in  character 


RHYNCHIPPUS  EQUINUS 


97 


between  the  premolars  and  the  succeeding  molars,  being 
only  slightly  rhomboidal  in  outline,  while  in  the  last  two 
molars  the  anterior  external  corner  is  markedly  prolonged. 
In  different  individuals,  the  lower  jaw  varies  greatly  in 
height,  but  this  seems  to  me  to  be  individual  and  sex  varia- 
tion. The  three  incisors  and  the  canine  are  subequal  in 


Fig.  54.     Left    upper   dentition, 
old  individual — 1/2  natural  size. 


Fig.  55-  Right  lower 
dentition  of  R.  equi- 
nus;  A,  of  a  young  in- 
dividual; B,  of  an  old 
individual — 1/2  natu- 
ral size. 


size,  closely  crowded,  and  each  with  a  small  cingulum  near 
the  base  of  the  enamel. 


MEASUREMENTS  OF  SKULL,  SPECIMEN  3191 

Skull,  length  from  front  of  nasal  to  back  of  lambdoidal  crest  211   mm. 

Skull,  width  across  zygomatic  arches  172   mm. 

Skull,  width  across  postorbital  processes  78  mm. 

Skull,  height  above  molar  2  84  mm. 

Dentition,  from  upper  inc.  I  to  molar  3  140  mm. 

Dentition,  from  lower  inc.  i  to  molar  3  136  mm. 

Mandible,  height  under  molar  2  35  mm. 

Mandible,  height  under  the  articulation  118  mm. 


98 


THE  DESEADO  FORMATION  OF  PATAGONIA 


The  atlas  and  axis  arc  wanting,  and  the  characteristics 
of  the  other  ccrvicals  have  been  given  under  the  generic 
description. 

MEASUREMENTS,  SPECIMEN  No.  3291. 

Cervical  3,  length  of  centrum  18  mm. 

Cervical  5,  length  of  centrum  18  mm. 

Cervical  6,  length  of  centrum  21  mm. 

Cervical  6,  height  from  base  of  centrum  to  top  of  spine  74  mm. 

Cervical  7,  length  of  centrum  21  mm. 

Cervical  7,  height  from  base  of  centrum  to  top  of  spine  55  mm. 

The  first  three  or  four  of  the  thoracic  vertebrae  are  rep- 
resented only  by  their  neural  arches  and  spines.  There 


Fig.  56.    Cervicals.  5,  6  and  7 — 1/2  natural 
size. 


Fig.  57.    Dorsal  6  and  7—1/2  nat- 
ural size. 


were  at  least  fifteen  in  the  series,  for  I  have  that  number 
represented,  but  more  probably  the  number  was  sixteen  as 
in  the  case  in  Adinotherium.  Typical  vertebrae  measure: 


SPECIMEN  3291 

Thoracic  3,  langth  of  centrum 

Thoracic  3,  height  from  base  of  centrum  to  spine 

Thoracic  6,  length  of  centrum 

Thoracic  6,  height  from  base  of  centrum  to  spine 

Thoracic  14,  length  of  centrum 

Thoracic  14,  height  from  base  of  centrum  to  spine 


21  mm. 
56  mm. 

22  mm. 
79   m  m . 
26  mm. 
65   mm. 


In  my  series,  there  are  six  lumbars,  which  is  one  more 
than  is  credited  to  Adinotherium,  though  in  that  genus  the 


RHYNCHIPPUS  EQUINUS 


99 


number  has  not  been  definitely  fixed.     Typical  lumbars 
measure  as  follows: 

Lumbar  2,  length  of  centrum 

Lumbar  2,  height  from  base  of  centrum  to  spine 

Lumbar  4,  length  of  centrum 

Lumbar  4,  height  from  base  of  centrum  to  spine 

There  is  nothing  to  represent  the 
sacrum  or  caudals. 

Only  the  lower  half  of  the  humerus 
is  preserved  and  that  with  specimen 
3191,  and  it  measures: 

Humerus,  diameter  of  shaft  22  mm. 

Humerus,  greatest  width  of  distal  end        46  mm. 
Humerus,  width  of  trochlea  36  mm. 


Fig.  58.    Humerus — 1/2 
natural  size. 


JY 


Fig.  59.    Right  front  foot — 1/2 
natural  size. 


The  distal  ends  of  the  radius  and  ulna  are  preserved  in 
specimen  3291,  as  they  were  found  in  association  with  the 
carpus. 

Radius,  diameter  of  the  distal  end  29  mm. 

Ulna,  diameter  just  above  styloid  process  21   mm. 

Ulna,  diameter  of  styloid  process  II   mm. 

The  carpus  is  carefully  drawn,  from  which  the  various 
measurements  may  be  obtained.  There  is  a  tendency  for 


100  THE  DESEADO  FORMATION  OF  PATAGONIA 

the  two  rows  of  carpals  to  alternate,  but  this  is  not  ad- 
vanced to  any  considerable  degree.  The  trapezium  is 
entirely  isolated  from  the  other  carpals,  and  lies  as  a  flat- 
tened scale,  on  the  side  of  the  upper  end  of  Me.  II. 

The  metacarpals  are  closely  crowded  together,  making 
a  compact  foot  with  very  little  freedom  of  motion  in  its 
upper  part.  The  three  carpals  are  of  nearly  equal  length, 
though  the  third  is  slightly  heavier  and  longer  than  the 


Fig.  61.    Pair  of  se- 

Fig.  60.    Digit  4  of  Rhynchippus  from  samoids    under     Me. 

the  side — 1/2  natural  size.  IV — 1/2  natural  size. 

others,  but  there  is  no  tendency  toward  a  further  reduction 
of  the  toes. 

Metacarpus  II,  length  67  mm. 

Metacarpus  III,  length  74  mm. 

Metacarpus  IV,  length  69  mm. 

Under  each  metacarpel  are  two  small  sesamoid  bones 
which  lie  either  side  of  the  low  crest  of  the  metacarpus. 
The  toes  are  all  short,  with  flattened  articular  ends,  which 
are  cut  under  in  a  very  oblique  manner.  The  second  pha- 
lanx is  much  shorter  than  the  others,  while  the  distal,  or 
ungual  phalanx,  is  the  longest  and  highest  of  the  three. 
Each  ungual  phalanx  is  cleft  by  a  deep  narrow  notch,  much 
more  suggestive  of  a  claw  than  a  hoof.  The  phalanges  of 
all  the  toes  are  subequal  in  size,  so  that  the  measurements 
of  the  middle  digit  are  given. 

First  phalanx  of  digit  III,  length  12  mm. 

Second  phalanx  of  digit  III,  length  8  mm. 

Third  phalanx  of  digit  III,  length  16  mm. 


RHYNCHIPPUS  EQUINUS 


101 


As  preserved,  the  femur  is  crushed,  and  the  distal  end 
of  the  rotular  trochlea  is  weathered  off,  but  all  the  other 
characters  are  well  preserved.  The  femur  is  slender,  with 


Fig.   62.     Right  femur  posterior 
side — 1/2  natural  size. 


Fig.  63.  Right  tibia 
and  fibula  posterior  side 
— 1/2  natural  size. 


Fig.    64.    Calcaneum — 
1/2  natural  size. 


a  small  rounded  head.  The  greater  trochanter  is  heavy 
but  does  not  project  above  the  head,  the  lesser  is  small  but 
well  marked;  and  the  third  is  usually  far  down  the  shaft. 
Of  the  two  condyles  the  inner  is  the  smaller  and  more 
convex. 


102  THE  DESEADO  FORMATION  OF  PATAGONIA 

SPECIMEN  3291 

Femur,  greatest  length  202  mm. 

Femur,  diameter  of  head  26  mm. 

Femur,  width  across  head  and  greater  trochanter  62  mm. 

Femur,  width  of  internal  condyle  16  mm. 

Femur,  width  of  external  condyle  24  mm. 

The  tibia  is  much  flattened  at  the  upper  end  and  tapers 
to  nearly  circular  in  section  in  the  distal  portion  of  the  shaft. 
It  is  fused  proximally  to  the  fibula,  but  free  distally. 

Tibia,  length  222  mm. 

Tibia,  greatest  width  proximally  51   mm. 

Tibia,  least  diameter  of  the  shaft  24  mm. 

Tibia,  diameter  of  distal  articular  end  23   mm. 

The  fibula  is  a  very  slender  bone,  with  the  distal  end 
swollen  and  heavy.  As  it  rises  from  the  carpus  it  is  so 
twisted  that  it  unites  with  the  upper  end  of  the  tibia  almost 
on  the  posterior  surface. 

Fibula,  diameter  of  the  articular  end  17  mm. 

Fibula,  least  diameter  of  the  shaft  10  mm. 

The  calcaneum  is  of  moderate  length,  and  very  stout, 
resembling  that  of  Adinotherium,  except  that  it  is  longer. 

Calcaneum,  length  64   in  in. 

Calcaneum,  width  28   mm. 

Of  the  hind  foot  there  is  preserved  only  the  distal  por- 
tions of  two  metatarsals,  which  are  about  the  same  size 
and  character  as  those  of  the  front  foot,  and  a  phalanx  of 
the  first  row,  also  similar  to  the  same  one  of  the  front  foot. 

Figure  65  gives  a  restoration  of  the  animal  based  on  the 
bones  described  in  the  foregoing  pages.  The  animal  in  all 
features  turns  out  a  typical  toxodont,  adapted,  by  the 
cropping  teeth,  and  the  broad-faced  premolars  and  molars, 
for  a  grazing  animal,  but  its  advancement  in  adapting 
itself  to  feeding  on  grass  has  not  proceeded  very  far,  as  is 
indicated  by  the  shortness  of  the  molars.  The  legs  are 
longer  than  in  the  other  families  of  the  toxodonts  which 
would  signify  that  it  had  developed  some  speed,  but  the 
feet  have  progressed  toward  the  modification  of  the  hoofs 


RHYNCHIPPUS  EQUINUS 


I03 


IO4 


THE  DESEADO  FORMATION  OF  PATAGONIA 


into  claws,  indicating  a  foot  more  like  that  of  a  dog,  in 
which  the  weight  is  not  carried  on  the  ungual  phalanges,  but 
rather  on  the  ball  of  the  foot,  or  bases  of  the  metapodials. 
I  should  not  feel  that  this  group  was  the  ancestral  one  to 
later  groups  of  toxodonts,  but  it  seems  rather  to  represent 
a  line  which  terminates  in  the  Deseado  or  very  little  later, 
not  having  run  up  into  the  Santa  Cruz.  The  line  of  an- 
cestry for  the  toxodonts  is  rather  through  Leontinidae. 


Rhynchippus  pumulis  Ameghino 

R.  pumulis  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  464. 

We  found  no  speci- 
mens of  this  species,  but 
Ameghino  has  described 
a  complete  skull,  a  fig- 
ure of  which  is  repro- 
duced here.  It  indicates 
a  smaller  lighter  built 
animal,  differing  from  R. 
equinus  not  only  in  small 
size,  but  also  in  having  a 
relatively  longer  and  nar- 
rower head.  The  indi- 
vidual is  a  rather  old 
one,  so  that  the  pits  in 
inc.  I  and  2  have  disap- 
peared, as  is  also  the 
case  with  the  cingulum 
on  the  ant.  int.  corners 
of  the  premolars.  Ame- 
ghino gives  the  follow- 
ing measurements  in  his 
description. 

Skull,  length  over  all  155  mm. 

Upper  dentition,  from  inc.  I  to  m.  3  80  mm. 


Fig.  66.  R.  pumulis — 1/2  natural  size;  A,  top  of  skull 
B,  upper  dentition,  after  Ameghino. 


MORPHIPPUS  105 

Rhynchippus  medianus  Ameghino 

R.  medianus  Amegh.,  1901,  Bol.  Acad.  Nac.  Cienc.  Cordoba,  t.  16,  p.  375. 

This  third  species  is  intermediate  in  size  between  the 
two  foregoing.  No  figure  is  given,  but  the  following  meas- 
urements give  the  size: 

Upper  molar  2,  length,  1 7  mm.,  width  n   mm. 

Length  of  lower  molars  I  to  3  40  mm. 

Height  of  mandible  under  m.  2  24  mm. 

These  figures  would  indicate  a  form  about  15  %  larger 
than  R.  pumulis,  and  35  %  smaller  than  R.  equinus. 

Morphippus  Ameghino 

Morphippus,  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  459. 

This  genus  is  very  similar  to  Rhynchippus,  with  the  same 
dental  formula,  the  same  grooves  in  the  upper  incisors,  and 
the  same  pattern  of  the  premolars  and  molars.  It  differs, 
however,  in  the  lower  incisors  having  no  cingulum  at  their 
base,  in  the  upper  molars  having  a  shallower  basin,  and  in 
bays  3  and  4  being  absent  from  the  lower  molars.  These 
features  simply  indicate  a  slightly  less  advanced  specializa- 
tion, less  hypsodont  teeth.  I  do  not  think  that  the  bays 
are  any  of  them  lacking  in  unworn  teeth,  but  in  a  less  hypso- 
dont tooth,  with  the  pits  extending  a  less  distance  into  the 
crown,  all  indication  of  the  bays  disappears  early. 

M .  imbricatus  is  described  as  the  type  species,  and  four 
others  have  been  described,  all  equal  in  size  to  M.  imbrica- 
tus, and  distinguished  by  the  teeth  being  slightly  more 
compressed,  by  the  external  cleft  of  the  lower  molars  being 
deeper,  or  by  variations  in  the  pits.  All  these  features  I 
consider  to  be  either  age  characters  or  individual  variations, 
so  that  all  five  species  of  this  genus  are  lumped  under  M. 
imbricatus. 


io6 


THE  DESEADO  FORMATION  OF  PATAGONIA 


Morphippus  imbricatus  Ameghino 

M.  imbricatus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  459. 

M.  hypsolodus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  461. 

M.  complicatus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  461. 

M.  fraternus  Amegh.,  1901,  Bol.  Acad.  Nac.  Cienc.  Cordoba,  t.  16,  p.  374. 

M.  quadrilobua  Amegh.,  i()<>i,  liol.  .\cad.  Nac.  Cienc.  Cordoba,  1.  16,  p.  374. 

The  general  characters  of  this  species  are  given  under 
the  generic  description  and  I  will  here  give  only  Ameghino's 
measurements  which  go  with  the  figure: 


Skull,  length  over  all 

Skull,  length  of  the  palate 

Upper  dentition,  length  the  inc.  I  to 

Diameter  of  the  palate  opposite  inc. 

Diameter  of  the  palate  opposite  in.  3 

Height  of  mandible  under  m.  I 


210  mm. 
120  mm. 
120  mm. 

37  mm. 

75  mm. 

33  mm. 


Kin.  "7-  M.  imbricatus — 1/2  natural 
size;  A,  upper  dentition;  /•',  louei  ilni- 
tition  after  Ameghino. 


Fig.  68.  K.  latirostris,  palatal  view,  after  a  pho- 
tograph of  the  type— 1/2 natural  si/e;  the  cross 
hatched  an-a  lepiesents  matrix  not  yd  removed. 


EURYGENIOPS  1 07 

Eurygeniops  Ameghino 

Eurygenium  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  655. 
Eurygeniops  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  464. 

The  name  first  given  this  genus  was  found  to  be  preoc- 
cupied, and  therefore  changed.  It  is  a  clear  cut  genus, 
differing  from  the  others  in  the  family  in  the  expansion  of 
the  front  of  the  muzzle,  and  by  the  heavy  broad  character 
of  the  skull. 

Eurygeniops  latirostris  Ameghino 

E.  latirostris  Amegh.,  loc.  cited  above. 

This  is  the  type  species  and  is  based  on  a  muzzle  which 
has  never  been  figured,  but  which  I  figure,  the  drawing 
being  made  from  a  photograph  taken  by  Professor  Scott 
and  kindly  furnished  me.  The  characters  of  the  species 
are  those  of  the  genus,  with  the  following  measurements 
for  specific  determination,  quoted  from  Ameghino: 

Palate,  length  130  mm. 

Palate,  width  between  incisors  3  41  mm. 

Palate,  width  between  premolars  2  33  mm. 

Palate,  width  between  molars  3  56  mm. 

Upper  dentition,  length  from  pm.  R.  to  m.  3  82  mm. 

Upper  premolar  4,  length  1 1  mm. 

Upper  premolar  4,  width  19  mm. 

Eurygeniops  normalis  Ameghino 

E.  normalis  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  466. 

This  second  species  is  described  as  being  much  smaller 
than  the  preceding,  the  length  from  pm.  4  to  molar  3  being 
65  mm. 


CHAPTER  VII 

LEONTINIDAE 

THIS  family  was  established  to  include  a  group  of  large, 
heavily  built  ungulates,  not  unlike  rhinoceroses  in  form, 
which  have  rooted  teeth,  the  molars  being  similar  to  those 
of  Rhinchippidae,  i.  e.,  composed  of  a  wall  and  an  anterior 
and  posterior  lobes,  but  with  the  cristae  either  lacking  or 
little  developed ;  and  with  the  second  upper,  and  the  third 
lower  incisors  developed  into  tush-like  caniniform  teeth. 
Two  genera  are  especially  abundant,  Leontinia  of  the  Des- 
eado  beds,  and  Colpodon  of  the  Colpodon  beds,  the  former 
with  the  formula  3^3,  the  latter  with  f^-j.  In  many 
ways,  the  family  suggests  Nesodontidae,  and  undoubtedly 
belongs  to  that  series,  if  not  directly  ancestral.  The  lower 
molars  are  distinctly  of  the  same  type  as  in  all  the  other 
toxodonts,  but  show  a  tendency  to  become  hyposodont. 

The  following  genera  have  been  assigned  by  Ameghino 
to  the  family.  Some  of  them  are  based  on  very  scant  mate- 
rial and  I  have  ventured  to  suggest  in  each  case  what  dis- 
position I  have  felt  to  be  the  proper  one. 

Leontinia,  the  type  genus,  is  described  in  detail  on  pages 
109-115. 

Scaphops  is  based  on  a  mandibular  symphysis,  which  is 
wider  than  usual  for  Leontinia,  and  on  a  second  upper 
incisor  which  is  compressed.  The  species  in  the  genus 
Leontinia  show  a  marked  degree  of  variability,  and  I  can 
see  in  this  only  individual  variability,  so  that  I  place  Scap- 
hops under  Leontinia  and  S.  grypus,  as  a  synonym  of  L. 
gaudryi. 

Steniogenium  is  based  on  a  mandibular  symphysis  with 
roots  only  of  the  teeth.  The  incisors  are  proclivous  and 
inc.  3  small.  I  consider  this  also  as  Leontinia,  and  the 
species  S.  sclerops  as  a  synonym  of  L.  oxyrhynca,  which  I 
think  is  the  female  of  L.  gaudryi. 


LEONTINIDAE  109 

Ancylocoelus  is  a  valid  genus,  differentiated  by  its  dental 
formula  f^fy,  the  loss  of  the  upper  canine  and  the  lower 
canine  and  first  premolar  distinguishing  it  from  either  Leon- 
tinia  or  Colpodon. 

Rodiotherium  is  based  on  a  mandibular  symphysis  which 
would  indicate  an  animal  with  the  same  formula  as  the 
foregoing  genus,  differing  only  in  that  lower  incisor  3  is 
large.  This,  to  my  mind,  does  not  make  a  generic  char- 
acter, and  at  most  the  species,  R.  armatum,  can  only  be 
considered  an  independent  species  belonging  to  the  genus 
Ancylocoelus. 

Loxocoelus  is  a  very  questionable  genus,  based  simply 
on  an  upper  molar,  which  "is  similar  to  that  of  Homolo- 
dontotherium,  but  more  squared."  I  feel  that  in  regard  to 
this  genus  it  should  stand  as  unknown  until  more  material 
is  found. 

In  our  collection,  over  twenty  skulls  and  jaws  belonging 
to  this  family  turned  up,  but  all  clearly  belong  to  two  types, 
the  typical  Leontinia  gaudryi,  and  some  others  in  which 
the  caniniform  teeth  are  not  so  well  developed,  which  are 
either  L.  oxyrhynca  or,  as  I  believe,  the  females  of  L.  gau- 
dryi.  It  is  this  uniformity  of  the  material  which  leads  me 
to  doubt  the  validity  of  the  considerable  number  of  genera 
which  Ameghino  has  established,  for  I  found  on  sectioning 
the  teeth  that  between  the  little  worn  crown  and  the  much 
worn  one  there  was  a  marked  difference  in  the  appearance 
of  the  infoldings  and  in  the  development  of  the  pits. 

Leontinia  Ameghino 

Leontinia  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  647. 
Leontinia  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  469. 
Scaphops  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  475. 
Steniogenium  Amegh.,  1895,  Inst.  Geog.  Argen.,  t.  15,  p.  654. 
Steniogenium  Amegh.,  1897,  Inst.  Geog.  Argen.,  t.  18,  p.  475. 
Colpodon  Gaudry,  in  part,  1906,  Anal.  Palaeontologie,  t.  I,  p.  30. 

The  formula  is  33]  \\  ;  type  species  L.  gaudryi.  Of  all 
the  animals  in  the  Deseado,  this  is  the  most  abundant. 


110  THE  DESEADO  FORMATION  OF  PATAGONIA 

I 'sing  this  species  as  a  basis,  the  following  are  the  charac- 
teristic features.  The  first  upper  incisor  is  a  small  crop- 
ping tooth,  with  a  well-developed  cingulum  high  up  on 
the  inner  face,  which,  when  the  tooth  is  worn  down  to  the 
proper  level,  unites  with  the  main  part  of  the  crown  and 
incloses  for  a  short  time  a  small  pit.  On  the  external  face 
there  is  also  a  feeble  cingulum  near  the  base  of  the  enamel. 
The  second  incisor  is  greatly  enlarged  into  a  caniniform 
tush.  In  the  species  L.  oxyrhynca,  this  tooth  is  much 
smaller  but  as  this  reduction  of  the  tushes  is  the  only  dif- 
ference, I  consider  these  forms  as  the  female.  The  third 
incisor  is  again  small,  and  has  a  well-developed  cingulum 
on  both  the  front  and  inner  faces.  The  canine  is  similar 
to  inc.  3. 

The  first  premolar  is  much  reduced  in  size,  with  a  weak 
cingulum  on  the  outer  face,  and  probably  another  on  the 
inner  side  (the  tooth  is  too  much  worn  in  my  specimen  to 
be  sure).  Beginning  \\ilh  premolar  2,  the  upper  teeth  are 
molariform.  The  premolars  are  rectangular  in  outline, 
each  being  much  wider  than  long,  and  each  having  a  cingu- 
lum on  the  outer  side.  On  the  inner  side,  along  the  anterior 
half  of  each  premolar,  there  is  a  high  cingulum,  which, 
though  interrupted  at  the  anterior  corner,  continues  around 
onto  the  anterior  face  of  the  tooth.  On  a  worn  tooth  this 
anterior  cingulum  unites  with  the  grinding  surface,  and 
leaves  a  small  pit  in  the  anterior  internal  corner,  which  is 
very  suggestive  of  Rhynchippidae.  In  the  middle  of  the 
grinding  surface,  there  is  an  oblique  pit,  the  remains  of  the 
basin  in  young  teeth.  The  molars  continue  to  increase  in 
vsize  toward  the  rear.  They  have  a  vestige  of  a  cingulum  on 
the  external  side,  no  cingulum  on  the  inner  side,  but  on  the 
anterior  side  for  about  one  third  the  distance  there  is  a 
cingulum  similar  to  that  on  the  premolars.  In  the  middle 
of  the  grinding  surface  is  an  elongated  oblique  pit,  similar 
to  that  in  the  premolars,  but  a  little  more  advanced,  there 
being  a  trace  of  the  development  of  cristae. 


LEONTINIA  III 

In  the  lower  dentition,  the  first  two  incisors  are  small 
cropping  teeth,  with  the  anterior  face  flattened  and  having 
a  trace  of  a  cingulum;  while  on  the  inner  face  the  cingulum 
is  well  developed.  Incisor  3  is  developed  into  a  tush  cor- 
responding to  inc.  2  in  the  upper  dentition.  As  in  the 
upper  teeth,  there  are  two  types,  that  of  L.  oxyrhynca  with 
the  tush  only  about  twice  the  size  of  an  incisor,  and  that 
of  L.  gaudryi  with  it  much  larger. 

All  the  premolars  are  molariform  and  of  the  typical  tox- 
odont  character,  consisting  of  two  crescents  with  a  pillar 
and  septum  in  the  posterior  crescent.  The  septum,  how- 
ever, does  not  appear  until  on  pm.  3  and  on  all  succeeding 
teeth,  and  is  usually  indicated  by  a  tiny  pit.  From  the 
front  to  the  back,  the  premolars  are  progressively  larger, 
each  having  a  cingulum  on  both  the  internal  and  external 
faces.  The  molars  continue  to  increase  in  size  progres- 
sively, and  have  the  same  characters  as  the  premolars, 
except  that  the  crescents  are  mqre  elongated,  and  the  cin- 
gula  are  gradually  becoming  smaller  toward  the  rear. 

The  skull  is  low  and  heavy,  with  a  low  sagital  crest,  and 
with  the  lambdoidal  crests  continuous  with  the  upper  mar- 
gin of  the  zygomatic  arches.  The  nasal  bones  are  short 
and  wide,  and  are  markedly  raised  above  the  nasal  cham- 
ber. On  the  outer  margin  of  each  is  a  low  boss,  somewhat 
as  on  the  nasals  of  the  rhinoceros,  Dicer atherium,  which 
would  indicate  that  this  form  had  a  small  pair  of  nasal 
horns.* 

The  frontal  bones  are  broad,  projecting  laterally  in  strong 
postorbital  processes,  which,  with  those  from  the  jugals, 
almost  close  the  orbit  behind.  The  premaxillae  are  pecu- 
liar in  having  a  median  crest  on  the  upper  surface,  the  top 
of  the  crest  being  rugose,  as  though  in  life  it  had  continued 
upward  as  a  cartilage  septum.  The  maxillae  rise  well  up 

*  Scott  has  restored  the  head  of  Leontinia  gaudryi  with  a  single  median  horn, 
but  no  specimen  in  my  collection  would  indicate  anything  but  a  pair  of  nasal 
horns.  See  Scott,  Mammals  of  the  Western  Hemisphere,  fig.  138,  1912. 


112  THE  DESEADO  FORMATION  OF  PATAGONIA 

on  the  sides  of  the  skull,  bounding  the  lower  part  of  the 
orbit,  and  having  a  short  zygomatic  process.  The  small 
lachrymal  is  but  little  exposed  on  the  exterior  surface  of 
the  skull,  the  lachrymal  pit  being  well  inside  the  orbit. 
The  zygomatic  arches  are  broad  and  heavy,  and  composed 
mostly  of  the  wide  jugal  bones.  The  palate  is  highly  arched 
and  relatively  narrow,  the  crowns  of  the  premolars  and 
molars  projecting  inward  over  it,  thus  narrowing  it  still 
more.  It  extends  back  well  beyond  the  last  molar.  The 
large  tympanic  bullae  are  hollow,  and  the  cavity  in  the 
squamosum  seems  to  be  reduced  in  size,  as  compared  with 
Rhynchippidae  or  Nesodontidae.  The  occipital  condyles  are 
set  well  apart  and  are  sessile;  and  the  paroccipital  proc- 
esses are  long  and  slender. 

The  atlas,  axis  and  cervical  3  are  associated  with  the 
skulls.  The  atlas  is  short,  heavy,  and  has  the  anterior 
cotyles  broad,  deeply  excavated  and  wide  apart;  while  the 
posterior  cotyles  are  nearly  flat,  and  high  as  well  as  wide. 
The  transverse  processes  are  only  moderately  wide,  but  are 
very  heavy,  especially  along  the  posterior  margin.  The 
centrum  of  the  axis  is  flattened,  the  neural  canal,  wider 
than  high,  and  the  neural  spine  of  moderate  height.  The 
anterior  cotyles  are  broad  and  moderately  convex,  and  the 
odontoid  process  is  a  stout  peg-like  process,  somewhat 
higher  than  wide.  Slender  transverse  processes  project 
sharply  from  the  centrum,  and  have  at  their  bases  a  large 
canal  for  the  vertebral  artery.  Cervical  3  is  shorter  than 
the  axis,  has  a  less  depressed  centrum,  a  small  neural  spine, 
and  short  wide  transverse  processes. 

Though  I  have  skulls  and  jaws  to  represent  some  twenty- 
five  individuals,  no  limb  material  was  found  in  direct  asso- 
ciation with  any  of  them.  However  we  did  find  a  humerus, 
radius  and  ulna  on  the  same  level  and  about  fifteen  feet 
front  one  of  the  skulls,  and  as  it  corresponds  in  size,  and  as 
humeri  of  this  type  are  the  most  abundant  skeletal  bones 
found  (as  is  also  the  case  with  the  skulls),  I  have  considered 


LEONTINIA  II3 

it  proper  to  associate  these  fore  limb  bones  with  these  skulls. 
The  humerus  is  a  stout  bone,  of  medium  length,  with  a 
large  sessile,  and  but  little  rounded  head.  The  external 
tuberosity  is  wide,  thick  and  projects  a  little  above  the 
head,  while  the  internal  tuberosity  is  so  small  as  to  be 
almost  negligible.  The  shaft  is  flattened  laterally  at  the 
upper  end,  but  distally  is  compressed  in  the  antero-pos- 
terior  direction.  The  supratrochlear  fossa  is  shallow,  the 
anconeal  deep,  but  there  is  no  foramen  connecting  them. 
The  external  condyle  is  small,  the  internal  much  larger. 
The  trochlea  is  narrow,  with  a  swollen  articular  area  for 
the  radius,  and  a  wider  saddle-like  one  for  the  ulna.  The 
ulna  is  a  stout,  nearly  straight  bone,  slightly  longer  than 
the  humerus.  The  olecranon  process,  though  large,  is  not 
excessive.  The  sigmoid  notch  makes  a  deep  semicircular 
cavity,  with  the  articular  facets  expanding  on  either  side. 
It  was  closely  fitted  to  the  radius  so  as  to  allow  little  or  no 
rotary  motion  of  the  forearm.  The  facet  for  the  radius  is 
a  narrow  band-like  area  just  below  the  sigmoid  notch.  The 
shaft  is  almost  rectangular  in  section.  Distally  the  ulna 
contracts  sharply  into  a  heavy  styloid  process,  on  the  end 
of  which  is  a  large  convex  facet  for  the  pyramidal,  which 
merges  without  interruption  into  the  facet  for  the  pisiform. 
The  radius  is  a  slenderer  bone,  with  a  relatively  small  prox- 
imal head,  but  distally  expanded  into  a  much  larger  articu- 
lar end.  My  specimen  is  considerably  weathered,  but 
shows  a  wide  shallow  articular  facet  for  the  humerus,  and 
a  band-like  facet  for  the  ulna,  but  otherwise  it  gives  little 
more  than  the  length. 

Of  the  hind  limb,  Gaudry*  figures  the  astragulus  and 
the  calcaneum,  the  former  short  and  with  a  low  trochlea, 
the  latter  also  short  and  with  a  broad  facet  for  the  fibula. 
Gaudry  also  states  that  the  foot  was  tridactyle  and  planti- 
grade, but  I  am  doubtful  of  the  plantigrade  feature. 

*  Anales  Palaeontologie,  1906,  t.  I,  p.  28. 


114  THE  DESEADO  FORMATION  OF  PATAGONIA 

Ameghino  has  made  six  species  of  this  genus,  L.  gaudryi, 
L.  fissicola,  L.  lapidosa,  L.  oxyrhynca,  L.  stenognatha,  and 
L.  garzoni.  All  of  the  first  five  are  described  as  of  the  same 
size  as  L.  gaudryi.  L.  garzoni  is  a  smaller,  about  60  per 
cent,  of  the  size  of  the  others.  Of  the  first  five  listed,  the 
first  three  have  the  large  incisor  and  I  consider  them  all 
L.  gaudryi.  L.  oxyrhynca  and  L.  stenognatha  are  described 
as  having  small  canines  and  I  believe  that  this  is  a  sexual 
difference  only,  so  have  considered  these  two  species  as 
also  belonging  to  L.  gaudryi,  but  females.  I  have  made  a 
careful  comparison  of  L.  gaudryi  and  L.  oxyrhynca  and  find 
them  identical  in  all  the  features  except  in  the  region  of  the 
canines  where  the  latter  is  weaker,  and  can  see  no  more 
than  sexual  differences.  Usually  with  this  weakness  of 
the  canine  goes  a  smaller  or  lighter  build  of  the  lower  jaw 
which  is  what  would  be  expected.  The  points  by  which 
the  various  species  were  differentiated  were,  beside  the  size 
of  the  canine,  the  presence  or  absence  of  pit  3,  and  the  vari- 
ation in  the  foldings  on  the  outer  sides  of  the  lower  molars, 
which  I  find  on  sectioning  a  tooth  appear  deeper  or  shal- 
lower according  to  whether  the  tooth  was  more  or  less 
worn. 

Leontinia  gaudryi  Ameghino 

L.  gaudryi  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  648. 

L.  gaudryi  Amegh.,  1897,  Bol.  Geog.  Argen.,  t.  18,  p.  472. 

Scaphops  grypus  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  629. 

Scaphops  grypus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  475. 

Steniogenium  sclerops  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  654. 

Steniogenium  sclerops  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  475. 

Leontinia  fissicola  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  474. 

L.  (Senodon)  lapidosa  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  649. 

Females 

L.  oxyrhynca  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  472. 

L.  stenognatha  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  474. 

Colpodon  gaudryi  Gaudry,  1906,  Anal.  Palaeontologie,  t.  I,  p.  30. 

This  species  is  represented  in  the  Amherst  Collection  by 
five  more  or  less  complete  skulls,  and  over  twenty  jaws, 


LEONTINIA   GAUDRYI 

being  by  far  the  commonest  fossil  of  the  Deseado  beds  on 
the  Chico  del  Chubut  River,  west  of  Puerto  Visser.  As 
mentioned  above,  there  are  two  types,  the  first,  with  larger 


Fig.  69.  Right  upper  dentition 
— 1/2  natural  size. 


Fig.  70.  Lower 
dentition  of  male 
— 1/2  natural  size. 


Fig.  71.  Lower  den- 
tition of  female — 1/2 
natural  size. 


canines  and  heavier  mandibles,  designated  by  Ameghino 
as  L.  gaudryi,  which  I  consider  males;  second,  those  with 
smaller  canines,  and  lighter  mandibles,  slightly  smaller  in 
size,  which  Ameghino  designated  L.  oxyrhynca  and  I  con- 


n6 


THE  DESEADO  FORMATION  OF  PATAGONIA 


sider  females.  Practically  all  of  the  other  species  are  based 
on  mandibular  symphyses  varying  in  details  from  the 
above,  but  in  no  case  sufficiently  for  me  to  see  a  specific 
variation. 

The  general  features  have  been  discussed  under  the 
generic  description.  Incisor  i  has  a  long  crown  and  a 
long  root,  and  is  greatly  crowded  by  the  tushes.  Incisor  3 
and  pm.  I  have  the  same  crowded  appearance.  In  giving 
the  measurements  I  have  used  a  skull  which  is  typically 
L.  gaudryi,  a  male,  and  parallel  to  it  have  put  another  skull, 
which  is  typically  L.  oxyrhynca,  the  female.  By  compar- 
ing the  two  sets  of  figures,  the  shortening,  of  which  Ame- 
ghino  speaks,  will  be  seen  to  be  all  in  the  region  of  the 
tushes. 

SPECIMEN  3290  SPECIMEN  329  ix 


MALE 


FEMALE 


Upper  dentition,  length  from  inc.  I  to  m.  3 
Upper  dentition,  length  from  pm.  I  to  m.  3 

Incisor  I,  length 

Incisor  2,  length 

Incisor  3,  length. 

Canine,  length 

Premolar  I,  length 

Premolar,  I  width 

Premolar  2,  length 

Premolar  2,  width 

Premolar  3,  length 

Premolar  3,  width 

Premolar,  4,  length 

Premolar  4,  width 

Molar  i,  length 

Molar  i,  width 

Molar  2,  length 

Molar  2,  width 

Molar  3,  length 

Molar  3,  width 
Lower  dentition,  height  of  mandible  under  m.  i 

Incisor  I,  length 

Incisor  2,  length 

Incisor  3,  length 

Canine,  length 

Premolar  i,  length 


227 

mm. 

1  80 

mm. 

12 

mm. 

25 

mm. 

I  I 

mm. 

12 

mm. 

12 

mm. 

18 

mm. 

18 

mm. 

28 

mm. 

20 

mm. 

34 

mm. 

22 

mm. 

20 

mm. 

38 

mm. 

34 

mm. 

28 

mm. 

24 

mm. 

40 

mm. 

38 

mm. 

36 

mm. 

33 

mm. 

48 

mm. 

45 

mm. 

46 

mm. 

46 

mm. 

48 

mm. 

47 

mm. 

66 

mm. 

56 

mm. 

8 

mm. 

8 

mm. 

10 

mm. 

10 

mm. 

23 

mm. 

13 

mm. 

8 

mm. 

9 

mm. 

13 

mm. 

8 

mm. 

LEONTINIA   GAUDRYI 


Premolar  I,  width 
Premolar  2,  length 
Premolar  2,  width 
Premolar  3,  length 
Premolar  3,  width 
Premolar  4,  length 
Premolar  4,  width 
Molar,  i,  length 
Molar  i,  width 
Molar  2,  length 
Molar  2,  width 
Molar  3,  length 
Molar  3,  width 


SPECIMEN  3290  SPECIMEN  3291  x 
MALE         FEMALE 

12 

mm. 

12 

mm. 

18 

mm. 

16 

mm. 

17 

mm. 

15 

mm. 

21 

mm. 

18 

mm. 

19 

mm. 

16 

mm. 

24 

mm. 

21 

mm. 

19 

mm. 

18 

mm. 

33 

mm. 

27 

mm. 

20 

mm. 

20 

mm. 

40 

mm. 

37 

mm. 

20 

mm. 

20 

mm. 

57 

mm. 

57 

mm. 

20 

mm. 

20 

mm. 

Fig.  72.    Top  view  of  skull  of  L.  gandryi  (female) — 1/4  natural  size. 


In  the  skulls  there  is  considerable  variation  in  size  in 
the  different  individuals,  but  the  proportions  remain  very 


n8 


THE  DESEADO  FORMATION  OF  PATAGONIA 


much  the  same  throughout.  In  the  female  the  snout  is 
relatively  a  little  shorter,  and  in  general  the  female  skulls 
are  from  5  to  10  per  cent,  smaller  throughout.  The  fol- 


Fig.  73.    L.  gandryi,  view  of  case  of  the  skull,  female  (L.  oxyhynea) — 1/4  natural  size;  Tym- 
pamic  bullae  broken  open. 


lowing  two  sets  of  figures  illustrate  the  comparative  sizes 
of  the  two  sexes. 


Skull,  greatest  length  front  to  back 
Skull,  greatest  width 
Skull,  length  of  nasal  bone 
Skull,  length  of  palate 


SPECIMEN  3335  SPECIMEN 

MALE  FEMALE 


420  mm. 
252  mm. 
115  mm. 
235  mm. 


392  mm. 
236  mm. 
102  mm. 
230  mm. 


LEONTINIA  GAUDRYI  119 

The  atlas  associated  with  skull  No.  3335  is  a  decidedly 
heavy  bone  in  all  its  proportions.  The  axis  and  the  third 
cervical  were  associated  with  skull  No.  329  ix,  and  are 
likewise  heavy  bones.  The  following  are  typical  meas- 
urements: 

Atlas,  greatest  length  86  mm. 

Atlas,  greatest  width  170  mm. 

Axis,  length  of  centrum  and  odontoid  process  132  mm. 

Axis,  length  of  odontoid  process  34  mm. 

Axis,  width  across  anterior  cotyles  98  mm. 

Cervical  3,  length  of  centrum  66  mm. 

Cervical  3,  width  of  posterior  end  of  centrum  55  mm. 


Fig.  74.    Atlas  seen  from  below — 1/4  natural       Fig.  75.    Axis  and  cervical  vertebra,  No.  3 — 1/4 
size.  natural  size. 

While  there  are  other  vertebrae  in  the  collection,  which 
probably  belong  to  this  species,  I  have  not  cared  to  make 
the  association  without  some  evidence  of  a  definite  char- 
acter. However,  in  the  case  of  a  fore  limb,  which  was 
found  fairly  near  one  of  the  skulls,  is  of  proper  size,  and 
because  this  humerus  occurs  with  something  like  the  fre- 
quency of  the  skulls,  I  have  been  convinced  that  it  belonged 
to  this  species,  and  so  described  it  under  the  genus.  This 
specimen  consists  of  the  two  humeri,  the  radius  and  the 
ulna,  No.  3328. 

Humerus,  greatest  length  314  mm. 

Humerus,  diameter  of  head  77  mm. 

Humerus,  transverse  diameter  of  the  shaft  43  mm. 

Humerus,  width  of  distal  end  116  mm. 

The  ulna  lacks  some  60  mm.  in  the  middle  of  the  shaft, 
but  when  fitted  to  the  radius  its  length  can  readily  be  ob- 


120 


THE  DESEADO  FORMATION  OF  PATAGONIA 


tained.     The   radius   is   considerably   weathered   so    that 
measurements  of  the  distal  end  are  only  approximate. 


Ulna,  length  over  all 

Ulna,  transverse  diameter  of  distal  end 

Radius,  length  over  all 


430  mm. 

58  mm. 

310  mm. 


Fig.  76.  Right  humerus 
from  the  posterior  side — 1/4 
natural  size. 


g.  78. 
mal  end  of  right 
radius — 1/4  natural 
size. 


Fig.  77.  Right  ulna  from  exter- 
nal side — 1/4  natural  size. 


ANCYLOCOELUS  121 

Leontinia  garzoni  Ameghino 

L.  garzoni,  Amegh.,  1896,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  650. 
L.  garzoni,  Amegh,,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  474. 

We  were  not  fortunate  enough  to  find  this  species,  but 
as  described  by  Ameghino  it  is  about  60  per  cent,  of  the 
size  of  L.  gaudryi.  The  type  is  a  lower  jaw,  for  which  the 
following  figures  are  given : 

Lower  dentition,  length  from  pm.  i  to  m.  3  120  mm. 

Lower  dentition,  length  from  pm.  I  to  pm.  4  45  mm. 

Lower  dentition,  length  of  pm.  4  15  mm. 

Lower  dentition,  length  of  m.  3  39  mm. 

Ancylocoelus  Ameghino 

Ancylocoelus  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  652. 
Ancylocoelus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  475. 
Rodiotherium  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  653. 
Rodiotherium  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  476. 

This  genus  differs  from  Leontinia  in  its  formula,  ~-~ 
but,  except  for  the  loss  of  these  canines  and  the  lower  pre- 
molars,  is  very  similar.  In  this  it  seems  to  approach  the 
line  which  gave  rise  to  Colopdon.  The  premolars  and 
molars  are  also  narrower  in  proportion  than  in  Leontinia. 
I  have  placed  Rodiotherium  also  under  this  genus  as  I  can 
not  see  a  generic  difference  in  the  descriptions.  However 
we  were  not  fortunate  enough  to  find  these  forms.  Ameg- 
hino has  described  four  species  as  follows: 

A.  frequens,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  475. 

Upper  dentition,  pm.  i  to  m.  3  150  mm. 

Lower  dentition,  pm.  2  to  m.  3  150  mm. 

Upper  molar  3,  length  39  mm. 

A.  lentus,  1901,  Bol.  Acad.  Nac.  Cordoba,  t.  16,  p.  407. 

Upper  molar  3,  length  48  mm. 

A.  minor,  1901,  loc.  cit. 

Upper  molar  3  34  mm. 

A.  (Rodiotherium)  armatum,  see  cit.  above. 

Based  on  an  imperfect  mandibular  symphysis,  in  which  incisor  3  is  very 
large. 


CHAPTER   VIII 

NESODONTIDAE 

THIS  family  is  characterized  by  the  teeth  being  hyp- 
sodont,  the  second  upper  incisor  and  the  third  lower  in- 
cisor being  enlarged  into  caniniform  teeth,  the  upper  molars 
complicated  by  the  development  of  cristae,  limbs  short, 
feet  tridactyl  and  semidigitigrade. 


Fig.  79.     A,  upper  and  a  lower  molars  2  of  Proadinotherium ;   B,  upper  and  b  lower  molars  2  of  Coresodon;   C 
upper  and  c  lower  molars  2  of  Neudon — -1/2  natural  size. 

In  the  Santa  Cruz,  the  family  is  represented  by  the  two 
genera  Nesodon  and  Adinotherium.  In  the  Deseado  we 
find  Proadinotherium  evidently  ancestral  to  Adinotherium 
and  very  little  differentiated  from  it.  Ameghino  has  de- 
scribed a  genus,  Pronesodon,  which  is  evidently  ancestral 
to  Nesodon.  I  have  referred  Coresodon  to  this  family  be- 
cause the  molars  of  the  upper  and  lower  jaws  are  very 
close  to  those  of  Adinotherium.  Ameghino  has  also  de- 
scribed two  genera,  Nesohippus  and  Interhippus,  based  on 
upper  molars  which  are  very  similar  in  pattern  to  Adi- 
notherium and  which  I  believe  belong  to  this  family,  if 
they  prove  to  be  valid  genera,  of  which  I  have  some  doubt, 
feeling  that  they  will  prove  to  be  the  deciduous  upper  pre- 


PROADINOTHERIUM  123 

molars  of  Proadinotherium  or  some  similar  form.  The 
genus  Senodon,  which  Ameghino  also  places  in  this  family, 
I  feel  will  prove  to  be  worn  teeth  of  Leontinia. 

Proadinotherium  Ameghino 

Proadinotherium  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  625. 

The  dental  formula  is  -fi-Jy,  as  in  Adinotherium,   the 
chief  difference  being  that  the  teeth  are  less  hypsodont 


Fig.  80.     P.  leptognathus,  rear  portion  of  skull — 1/2  natural  size;    shaded  areas  are  matrix. 

than  in  the  Santa  Cruz  genus.  Little  is  known  as  yet  of 
the  skeleton,  but  when  more  is  known  probably  more  dis- 
tinctive characters  will  appear.  Ameghino  made  two 
species,  P.  leptognathus  which  we  also  found,  and  P.  angus- 
tidens  a  much  smaller  form. 


124  THE    DESEADO   FORMATION   OF    PATAGONIA 

Proadinotherium  leptognathus  Ameghino 

P.  leptognathus  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  625. 
P.  leptognathus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  467. 

Of  this  species  we  found  on  the  Chico  del  Chubut  River, 
west  of  Puerto  Visser,  three  specimens;  the  back  of  a  skull 
as  far  forward  as  molar  2,  and  two  lower 
jaws.  In  general,  the  species  is  very 
similar,  even  to  size,  to  Adinotherium 
ovinum  of  the  Santa  Cruz. 

The  upper  molars  are  strongly  hypso- 
dont,  curved  teeth.  On  the  upper  surface, 
the  basin  is  subdivided  by  two  strong 
cristae  into  three  smaller  bays.  In  an 
early  stage  of  wear,  the  second  crista 
unites  with  the  posterior  lobe,  convert- 
ing bay  3  into  a  pit.  On  the  posterior 
margin  of  the  tooth,  the  cingulum  is  de- 
veloped so  as  to  appear  like  a  third  crista, 
^  which  inclosed  bay  4,  and  when  the  tooth 

— 1/2  natural  size.  •  11  i 

is  worn,  bay  4  becomes  a  pit  also. 

In  my  lower  jaw  incisor  3  is  developed  into  a  strong 
caniniform  tush.  Most  of  the  teeth  are  lacking,  but 
lower  molar  2  is  a  strongly  compressed,  hypsodont  tooth, 
surrounded  by  a  thick  layer  of  enamel.  This  tooth  rises 
22  mm.  above  the  well-developed  roots,  and  is  already 
considerably  worn  down.  The  pillar  is  prominent  as  a 
strong  fold  in  the  middle  of  the  posterior  crescent.  In 
this  specimen  there  is  no  trace  of  the  usual  pit  (3)  indi- 
cative of  the  septum,  but  I  should  expect  to  find  it  in  a 
younger  specimen.  The  mandible  broadens  in  front  into  a 
scoop-like  anterior  end,  and  the  alveoli  of  the  first  two  in- 
cisors would  indicate  that  they  were  proclivous.  The  alve- 
oli for  the  other  teeth  are  aranged  as  in  Adinotherium. 


PRONESODON  125 

MEASUREMENTS 

Skull,  width  across  the  zygomatic  arches  148  mm. 

Skull,  width  across  opposite  m.  3  (outside)  73  mm. 

Upper  dentition,  molar  2,  length  25  mm.,  width  13  mm. 

Upper  dentition,  molar  3,  length  23  mm.,  width  12  mm. 

Lower  dentition,  incisor  3,  length  13  mm.,  width  7  mm. 

Lower  dentition,  molar  2,  length  20  mm.,  width  7^  mm. 

Proadinotherium  angustidens  Ameghino 

P.  angustidens  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  467. 

This  is  based  on  a  single  lower  tooth,  which  is  considered 
either  pm.  4  or  m.  I,  and  measures  13  mm.  long  by  4^  mm. 
wide. 

Pronesodon  Ameghino 

Pronesodon  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  626. 

The  genus  is  said  to  resemble  Proadinotherium,  but  with 
the  caniniform  incisors  proportionally  much  shorter.  An 
associated  calcaneum  is  shorter  than  that  of  Adinotherium 
and  longer  than  that  of  Nesodon. 

Two  species  are  described. 

Pronesodon  cristatus  Ameghino 

P.  cristatus  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  626. 
P.  cristatus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  467. 

This  species  is  very  imperfectly  known,  is  characterized 
by  a  large  external  anterior  style,  molars  said  to  be  15  mm. 
wide. 

Pronesodon  robustum  Ameghino 

P.  robustum  Amegh.,  loc.  cit.  above. 

This  is  a  larger  species,  of  which  the  three  lower  molars 
are  known,  and  which  measure  16,  22,  and  30  mm.  in  length 
respectively,  while  they  are  9-10  mm.  wide. 


126 


THE   DESEADO   FORMATION   OF    PATAGONIA 


Coresodon  Ameghino 

Coresodon  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  630. 
Coresodon  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  459. 
Coresodon  Gaudry  in  part,  1908,  Anal.  Palaeontologie,  t.  I,  p.  46. 

In  this  genus,  the  pattern  of  the  upper  molars  is  essen- 
tially the  same  as  in  Proadinotherium,  and  they  are  of  the 
same  hypsodont  character,  and  with  roots.  I  can  now 
find  only  the  fact  that  in  Coresodon  the  teeth  are  more 
compressed  and  somewhat  more  hypsodont,  as  a  feature 
by  which  to  distinguish  this  genus  from  Proadinotherium. 
Gaudry  figures  the  front  of  a  lower  jaw  under  the  name 
Coresodon  which  lacks  the  caniniform  incisors.  I  have 
doubted  the  association,  but  should  it  prove  correct,  then 
this  genus  would  be  markedly  different  in  that  respect. 
Two  species  have  been  described,  C.  scalpridens,  and  C. 
cancellatus,  both  of  which  I  consider  the  same. 


Coresodon  scalpridens  Ameghino 

C.  scalpridens  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  630. 
C.  scalpridens  Amegh.,  1897,  Bol.  Inst.,  Geog.  Argen.,  t.  18,  p.  459. 
C.  cancellatus  Amegh.,  1901,  Bol.  Acad.  Nac.  Cienc.  Cordoba,  t.  16,  p.  374. 

Of  this  species  we  found  two  specimens,  one  containing 
the  three  lower  molars,  the  other  the  second  lower  molar 


O  o 


C 


D 


Fig.  82.    Sections  of  second  lower  molar;  A ,  top;  B,  4  mm.  down;  C,  10  mm.  down; 
D,  1 8  mm.  down — natural  size. 

only.  In  establishing  C.  cancellatus,  Ameghino  says  it  is 
of  the  same  size  as  C.  scalpridens,  but  distinguished  by  the 
basin  in  the  upper  molars  being  narrower,  the  internal 
fold  not  being  bifurcated,  and  by  the  absence  of  islets  of 


CORESODON 


127 


Fig.  83.  Molars  i  to  3 — natural  size 


enamel.     All  these  features  seem  to  me  to  be  the  results 
of  wear. 

While  the  pattern  of  the  upper  molars  is  the  same  as  in 
Proadinothcritim,  these  teeth  are  about  as  wide  as  they  are 

long.  The  lower  molars, 
however,  are  more  com- 
pressed, with  the  ante- 
rior crescent  occupying 
about  a  third  of  the  tooth,  and  having  in  the  early  stages  a 
deep  pit,  which  disappears  when  the  tooth  is  worn  down. 
In  the  middle  of  the  basin  of  the  posterior  crescent  is  a 
large  pillar,  and  between  this  and  the  median  horn  of  the 
crescent  is  a  tiny  septum,  which  early  unites  with  the  pillar, 
leaving  a  tiny  pit  (3)  which  soon  disappears  entirely.  In 
fact,  in  an  old  tooth,  the  second  and  fourth  bays,  having 
become  pits,  may  even  be  lost  also. 


MEASUREMENTS 

Upper  dentition,  molar  I,  length 

Upper  dentition,  molar  i,  width 

Upper  dentition,  m.  i  to  m.  3,  length 

Lower  dentition,  premolar  2,  length 

Lower  dentition,  premolar  3,  length 

Lower  dentition,  premolar  4,  length 

Lower  dentition,  molar  I,  length  18  mm.,  width 

Lower  dentition,  molar  2,  length  19  mm.,  width 

Lower  dentition,  molar  3,  length  20  mm.,  width 


Interhippus  Ameghino 

Interhippus  Amegh.,  1904,  Anal.  Mus.  Nac.  Buenos  Aires,  ser.  3,  t.  3,  p.  183. 
Interhippus  Amegh.,  1904,  Anal.  Soc.  Cienc.  Argen.,  t.  56,  p.  34  of  reprint. 

This  genus  was  established  on  isolated  teeth  which  closely 
resemble  those  of  this  family,  though  the  genus  was  placed 
among  the  Rhynchippidae  by  Ameghino.  The  teeth  de- 
scribed as  molars  are  much  elongated  and  have  the  cristae 
greatly  developed,  and  in  one  species  there  is  a  style  rising 
about  the  middle  of  the  inner  side  of  the  molar.  Another 
feature  emphasized  as  characteristic  of  this  and  the  next 


19  mm. 

@  Ameghino. 

12  mm. 

@  Ameghino. 

52  mm. 

@  Ameghino. 

13  mm. 

@  Ameghino. 

13  mm. 

@  Ameghino. 

17  mm. 

@  Ameghino. 

7  mm. 

7  mm. 

7  mm. 

128 


THE   DESEADO   FORMATION   OF   PATAGONIA 


genus  is,  that  the  crowns  are  expanded  much  wider  than 
the  roots.  While  there  is  not  yet  enough  direct  evidence 
to  prove  it,  I  feel  that  this  and  the  next  genus  will  prove 
to  be  deciduous  teeth,  of  either  Proadinotherium  or  some 
related  genus.  Two  species  of  this  genus  have  been  de- 
scribed, both  from  the  upper  Deseado. 
I.  phorcus  Amegh.,  loc.  cit.  above. 

This  species  is  characterized  by  its  size,  the  last  upper 
molar  (so  called)  measuring  16  mm.  long  by  14  mm.  wide. 
I.  deflexus  Amegh.,  1904,  Anal.  Mus.  Nac.  B.  A.,  ser.  3, 
t.  3,  P.  183. 

This  species  is  based  on  a  worn  tooth  designated  as  molar 
I  (probably  d.  pm.  3)  14  mm.  long  by  19  mm.  wide. 


Fig.  84.  I.  phorcus. 
"Upper  molars" — natural 
size,  after  Ameghino. 


Fig.  85.  I.  deflexus, 
"  Upper  molar  i " — natural 
size,  after  Ameghino. 


Fig.  86.  N.  insulattis, 
"Upper  molar  i"— natural 
size,  after  Ameghino. 


Nesohippus  Ameghino 

Nesohippus  Amegh.,  1904,  Anal.  Soc.  Cienc.  Argen.,  t.  56,  p.  34  of  reprint. 
Nesohippus  Amegh.,  1904,  Anal.  Mus.  Nac.  B.  A.,  ser.  3,  t.  3,  p.  218. 

This  genus  is  described  as  very  like  the  foregoing,  but 
differs  in  having  a  strong  perpendicular  style  on  the  ante- 
rior external  face  of  the  upper  molars.  As  in  the  preced- 
ing genus,  the  crown  is  considerably  expanded  above  the 
roots.  I  feel  that  this  genus  will  also  prove  to  be  the  milk 
teeth  of  some  one  of  the  genera  of  this  family.  One  species 
is  described,  based  on  a  single  tooth. 
N.  insulatus  Amegh.,  1904,  loc.  cit.  under  the  genus. 

The  species  is  just  as  described  under  the  genus,  the  last 
upper  molar  measuring  24  mm.  long  by  16  mm.  wide;  given 
as  from  the  upper  Deseado. 


CHAPTER  IX 

ISOTEMNIDAE 

THIS  family  is  distinguished  by  the  formula  -f-j-J-f-, 
by  the  incisors,  canine  and  premolar  I  all  being  of  subequal 
size,  by  all  the  teeth  being  brachydont,  and  by  the  cres- 
cents of  the  lower  premolars  and  molars  being  modified. 
On  these  lower  premolars  and  molars  the  anterior  crescent 
is  longer  than  the  posterior,  and  the  short  posterior  cres- 
cent on  the  exterior  of  the  tooth;  so  that  its  anterior  horn, 
instead  of  uniting  with  the  posterior  horn  of  the  anterior 
crescent,  comes  in  back  to  about  the  middle  of  the  anterior 
crescent.  Then  the  pillar,  which  in  the  other  families  is 
situated  in  the  posterior  crescent,  is  opposite  the  posterior 
horn  of  the  posterior  crescent.  The  small  animals  which 
represent  this  family  are  rare  in  the  Deseado  beds,  much 
more  abundant  in  the  Casamayor.  The  family  seems  to 
have  died  out  in  the  Deseado  as  no  forms  are  referred 
to  it  in  later  epochs.  We  found  no  specimens  belonging  to 
the  family;  but  to  make  this  discussion  complete,  I  will 
give  a  digest  of  Ameghino's  descriptions,  with  reproductions 
of  such  figures  as  he  has  given.  All  of  the  genera  and 
species  are  based  on  very  fragmentary  material. 

The  genera  assigned  to  the  family  are  Trimerostephanos, 
Pleurocoelodon,  Lophocoelus  and  Henricofilholia. 

Trimerostephanos  Ameghino 

Trimerostephanos  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  646. 
Trimerostephanos  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  483. 

This  genus  is  based  on  upper  and  lower  teeth,  and  dis- 
tinguished by  the  premolars  and  molars  having  a  weak 
style  on  the  anterior  corner,  and  by  the  anterior  lobe  being 
considerably  larger  than  the  posterior.  Four  species  have 
been  described. 


1 3o 


THE   DESEADO   FORMATION   OF   PATAGONIA 


T.  scabrus  Amegh.,  loc.  cit  for  genus. 

This  is  the  type  species,  originally  based  on  the  third 
lower  molar,  to  which  was  later  added,  upper  prernolar  4 


Fig.  87. 


T.  scabrus  —  natural  size;  /i,  upper  premolar  4;  B,  lower 
molars  i  and  2. 


The  following  measure- 


and  the  molars,  and  lower  molar  2. 
ments  are  given: 

Upper  premolar  4,  length  15  mm.,  width        21   mm. 

Upper  molar  2,  length 
Upper  molar  3,  length 
Lower  molar  2,  length 
Lower  molar  3,  length 

T.  scalaris  Amegh.,  1897,  Bol.  Tnst.  Geog.  Argen.,  t.  18, 
p.  483,  is  based  on  lower  pm.  2  to  m.  2,  a  somewhat  smaller 
species  than  the  preceding,  the  series  as  given  measuring 
53  mm. 


15  mm. 
31  mm. 
35  mm. 
20  mm. 
29  mm. 


Fig.  88.    T.  scalaris,  premolar  2  to  molar  2 — natural  size. 

T.  angustus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18, 
p.  484. 

This  species  is  described  without  a  figure,  as  smaller 
than  T.  scalaris,  pm.  2  to  m.  2  being  59  mm.  The  mandible 
is  also  slenderer. 


PLEUROCOELODON  131 

T.  biconus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18.  p. 
484.  ^ 

This  species  is  based  on  two  lower  premolars,  said  to  be 
the  same  size  as  T.  angustus,  but  with  the  pillar  larger. 

Pleurocoelodon  Ameghino 

Pleurocoeloclon,  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  645. 
Pleurocoelodon,  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  484. 

This  genus  is  distinguished  by  the  absence  of  the  style 
on  the  anterior  external  margin  of  the  upper  molars,  in- 


Fig.  89.    P.  wingei — natural  size;  A,  first  molar; 
B,  third  molar. 

stead  of  which  the  external  face  is  excavated  medianly. 
Two  species  are  described,  based  on  isolated  upper  teeth. 

P.  wingei  Ameghino 

P.  wingei  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  645. 
P.  wingei  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  485. 

This  species  is  founded  on  a  couple  of  isolated  molars, 
probably  belonging  to  the  same  individual.  The  following 
measurements  are  given: 

Upper  molar  I,  length  22  mm.,  width  26  mm. 

Upper  molar  3,  length  24  mm.,  width  29  mm. 

P.  cingulatus  Amegh.,  loc.  cit.  above,  is  based  on  an  in- 
complete upper  molar,  probably  the  second,  which  is  dis- 
tinguished by  having  the  internal  cingulum  excessively 
developed.  It  measures  30  mm.  in  length. 


132  THE   DESEADO   FORMATION   OF   PATAGONIA 

Lophocoelus  Ameghino 

Lophocoelus  Amegh.,  1904,  Anal.  Soc.  Cient.,  Rep.  Argen.,  t.  58,  p.  245. 
Lophocoelus  Amegh.,  1904,  Anal.  Mus.  Nac.,  ser.  3,  t.  3,  p.  352. 

The  genus  is  founded  on  a  single  upper  third  molar  from 
Mazaredo,  which  is  distinguished  by  a  feeble  style  on  the 
external  face,  by  the  anterior  lobe  being  obliquely  placed, 
and  by  the  presence  of  a  small  secondary  bay  on  the 
posterior  side  of  the  great  internal  basin. 

L.  macrostomus  Amegh.,  loc.  cit.  above. 

This  species  is  the  only  one  described,  and  has  the 
generic  features,  the  upper  m.  3  being  21  mm.  long,  by  25 
mm.  wide. 

Henricofilholia  Ameghino 

Henricofilholia  Amegh.,  1901,  Bol.  Acad.  Nac.  Cordoba,  t.  16,  p.  404. 

The  type  species  is  H.  cingulata,  based  on  a  single  upper 
molar.  In  general  the  upper  molars  are  similar  to  those 
of  Leontinia,  but  more  brachydont,  and  with  the  internal 
cingulum  well  developed  and  tending  to  be  crenulated. 
Four  species  have  been  made,  all  based  on  isolated  upper 
molars. 

Henricofilholia   cingulata 

Ameghino 

H.   (?   Parastropotherium)   cingulata  Amegh.,  Bol. 

Inst.  Geog.  Argen.  t.  15,  p.  640. 
H.  (?  Parastropotherium)  cingulata  Amegh.,   1897, 

Fig.  90.     ILdulata.  upper  Bo1'  Inst'  Ge°g"  ArSen'  4-  l8»  P'  45<>. 

molar  r  — natural  size,  after    H.  cingulata  Amegh.,  igoi,  Bol.  Acad.  Nac.  Cienc. 

Ameghino.  ^       ,    , 

Cordoba,  t.  16,  p.  404. 

This  is  based  on  an  upper  molar  I  of  which  I  reproduce 
Ameghino's  figure.  It  measures  28  mm.  long  by  29  mm. 
wide. 


HENRICOFILHOLIA  133 

H.  lustrata  Amegh.,  1901,  Bol.  Acad.  Cienc.  Cordoba,  t. 
1 6,  p.  405. 

This  species  is  smaller  than  the  preceding,  and  is  based 
on  an  upper  molar  i  and  a  last  lower  molar.  The  measure- 
ments are  as  follows: 

Upper  molar  I,  length  25  mm.,  width  25  mm. 

Lower  molar  3,  length  25  mm.,  width  12  mm. 


Fig.  91.    H,  inaequilatera,  upper  molars  3  and  4 — natural 
size,  after  Ameghino. 

H.  inaequilatera  Amegh.  loc.  cit.  above. 

This  species  is  larger  than  the  preceding  with  the  in- 
ternal cingulum  more  developed.  Upper  molar  2  measures 
30  mm.  long  by  29  mm.  wide. 

H.  circumdata  Amegh.,  loc.  cit.  above. 

This  is  a  still  larger  type,  with  the  internal  cingulum 
enormously  developed.  Upper  molar  I  measures  42  mm. 
long  by  36  mm.  wide. 


CHAPTER  X 

HOMALODONTOTHERIA 

THE  forms  making  up  the  Homalodontotheria  are  char- 
acterized by  a  dentition  which  is  clearly  a  derivative  of 
that  of  Toxodontia,  but  is  distinguished  by  the  teeth  being 
brachydont,  by  the  canines  being  the  teeth  which  tend  to 
become  tush-like,  though  not  advancing  to  a  marked 
degree.  But  the  distinctive  feature  of  the  suborder  is 
found  in  the  feet,  which  are  clawed,  the  ungual  phalanges 
being  deeply  cleft;  and  further,  the  animals  seem  to  have 
walked  on  the  sides  of  the  foot,  suggesting  the  Ancylopoda; 
but  there  does  not  seem  to  have  been  a  phylogeretic  re- 
lationship, rather  it  is  a  case  of  parallel  development. 
Most  of  the  forms  found  are  of  considerable  size,  and  they 
are  relatively  scarce  in  all  the  formations. 

The  representatives  of  the  group  in  the  Deseado  all 
belong  to  the  genus  Asmodeus,  which  seems  to  be  directly 
ancestral  to  the  Santa  Cruz  genus  Homalodontotherium, 
which  seems  to  be  the  last  representative  of  the  series,  no 
specimens,  referable  to  the  suborder  having  been  found 
in  later  beds. 

Asmodeus  Ameghino 

Asmodeus  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  643. 
Asmodeus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  476. 

The  formula  is  S  T  I  f ,  the  upper  incisors  have  pits 
in  the  crowns;  the  canines  are  moderately  enlarged;  the 
upper  premolars  and  molars  consist  of  an  external  wall, 
with  an  anterior  and  posterior  lobe,  the  lower  premolars 
and  molars  are  typically  like  those  of  toxodonts.  Two 
species  have  been  distinguished,  a  larger,  A.  osborni,  and 
a  smaller,  A.  scotti.  Our  collection  contains  seven  speci- 
mens, all  of  which  should  apparently  be  assigned  to  A. 
osborni. 


ASMODEUS  OSBORNI  135 

Asmodeus  osborni  Ameghino 

A.  osborni  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  644. 
A.  osborni  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  478. 
Homalodontotherium  osborni  Gaudry,  1906,  Anal.  Palaeontologie,  t.  I,  p.  II. 

The  type  of  this  species  is  a  calcaneum  and  astragulus, 
to  which  Ameghino  later  assigned  the  rear  part  of  a  mandi- 
ble with  pm.  4  and  the  three  molars;  also  a  milk  dentition, 
this  last  I  think  wrongly,  for  it  is  too  small.  I  should 
interpret  this  specimen  as  deciduous  inc.  2  to  deciduous 
pm.  4,  plus  permanent  molar  i,  in  which  case  the  permanent 
molar  corresponds  to  that  of  A.  scotti  and  it  is  not  necessary 
to  discuss  "the  remarkable  bicuspid  canine,"  as  Ameghino 


Fig.  92.  Molars  1-3  of  the  left  side — 1/2  natural  size. 

does.  Gaudry  had  some  of  this  material,  upper  molars, 
the  lower  end  of  the  humerus,  the  ulna,  calcaneum  and 
astragulus,  and  he  referred  the  genus  as  the  same  as 
Homoladontotherium.  With  this  last,  I  can  not  agree. 
We  found  the  three  upper  molars,  the  lower  end  of  the 
humerus,  part  of  the  radius,  the  tibia,  and  two  phalanges, 
all  on  the  Chico  del  Chubut,  west  of  Puerto  Visser. 

While  brachydont,  the  external  faces  of  the  molars  are 
high,  and  each  has  a  tiny  cingulum  along  the  base  of  the 
crown.  There  is  also  a  strong  cingulum  around  the 
anterior,  internal,  and  posterior  faces  of  the  crown,  which 
on  the  posterior  margin  flares  out,  making  a  marked  and 
characteristic  ridge.  The  grinding  surface,  with  its  ex- 
ternal wall  and  two  transverse  lobes,  is  very  similar  to  the 
molar  of  a  rhinoceros.  When  the  tooth  wears  down,  the 


136 


THE   DESEADO   FORMATION   OF   PATAGONIA 


inclosed  basin  becomes  a  large  pit.  Between  the  posterior 
lobe  and  the  flaring  cingulum  on  the  posterior  margin, 
there  is  also  a  small  posterior  bay,  which,  in  an  old  tooth, 
will  also  appear  as  a  pit,  but  being  shallow,  it  does  not 
last  long. 

The  lower  molars,  as  figured  by  Ameghino,  are  of  the 
same  type  as  those  of  the  toxodonts,  consisting  of  two  cres- 
cents with  the  pillar  in  the  middle  of  the  posterior  cres- 
cent, but  the  crescents  and  pillar  are  very  plump;  so  that 
with  wear  they  form  broad  grinding  surfaces;  and  the 
bays,  instead  of  becoming  pits,  first  appear  as  notches, 
then  disappear  entirely.  Each  premolar  and  molar  has  a 
cingulum  on  the  internal  and  external  sides. 


Fig.  93.  Premolar  4  to  molar  3 — 1/2  natural  size,  after  Ameghino. 


MEASUREMENTS,  SPECIMEN 

Upper  dentition,  molar  i,  length 

Upper  dentition,  molar  2,  length 

Upper  dentition,  molar  3,  length 

Lower  dentition,  from  Ameghino's  measurements 

Lower  dentition,  premolar  4,  length 

Lower  dentition,  molar  I,  length 

Lower  dentition,  molar  2,  length 

Lower  dentition,  molar  3,  length 


3179 

46  mm.,  width  50  mm. 

51  mm.,  width  55  mm. 

50  mm.,  width  51  mm. 

28  mm.,  width  23  mm. 

34  mm.,  width  24  mm. 

46  mm.,  width  24  mm. 

76  mm.,  width  23  mm. 


Only  the  distal  end  of  the  scapula  has  been  found;  and 
this  shows  a  shallow  glenoid  cavity,  which  is  much  longer 
in  the  antero-posterior  direction,  than  in  the  transverse. 
The  spine  rises  close  above  the  rim  of  the  glenoid,  and  is 
unusually  heavy. 

The  lower  half  of  the  humerus  is  present,  and  character- 
ized by  very  wide  epicondyles,  a  shallow  supratrochlear 
fossa,  a  moderately  deep  anconeal  fossa,  no  foramen,  and 
a  wide  shallow  trochlea.  The  ulna,  according  to  Gaudry, 
is  a  long,  heavy,  nearly  straight  bone,  with  a  shallow  sig- 


ASMODEUS  OSBORNI 


137 


moid  notch,  and  with  a  large  olecranon  process  which  is 
not  bent  backward  to  any  marked  degree.     The  proximal 


Fig.  94.  Humerus,  anterior  side — 
i/5  natural  size. 


Fig.  95.  Ulna  anterior  side — 
i/5  natural  size,  after  Gaudry. 


end  of  the  radius  has  a  broad  doubly  curved  articular 
surface  to  fit  the  full  width  of  the  humeral  trochlea.  Its 
ulna  facet  is  a  short  broad  area  just  below  the  margin  of 
the  bone,  and  would  indicate  little  or  no  rotary  motion  of 


138 


THE  DESEADO  FORMATION  OF  PATAGONIA 


the  fore  arm.     Most  of  the  shaft  is  lacking  but  what  is 
present  indicates  a  very  slender  bone. 

The  tibia  is  also  a  rather  light  bone  of  moderate  length, 
and  is  strongly  curved  inward,   the  inner  margin  being 


Fig.  96.  Upper  end  of 
radius,  ulnar  side — 1/5 
natural  size. 


Fig.  98.   Astragalus,  dorsal  aspect — 1/2 
natural  size,  after  Ameghino. 


Fig.  97-  Left  tibia,  posterior 
side — i/s  natural  size. 


Fig.  99.  A,  Ungual  phalanx, 
No.  3;  B,  Ungual  phalanx,  No. 
5  i/2  natural  si/e. 


especially  concave.  On  the  wide  proximal  end,  the  inner 
condyle  is  concave,  the  outer  convex,  the  two  being  sep- 
arated by  a  prominent  bifid  spine.  The  shaft  is  slender, 
with  a  deep  groove  down  the  anterior  face  especially  at  the 


ASMODEUS  OSBORNI  139 

upper  end,  while  on  the  posterior  face,  there  is  a  large 
interosseus  crest,  which  starts  just  below  and  external  to 
the  spine,  and  extends  in  a  sigmoid  curve  three-fourths  of 
the  length  of  the  shaft,  ending  on  the  internal  border 
Distally  the  tibia  is  flattened  antero-posteriorly,  and  the 
internal  margin  extends  as  a  wide  process  down  to  the 
level  of  the  navicular  face  of  the  astragulus.  The  articular 
facet  for  the  astragulus  is  a  rectangular  depression,  being 
about  half  as  wide  in  the  an tero- posterior  direction  as  in 
the  transverse.  This  facet  is  only  slightly  concave  and  the 
inner  and  outer  portions  are  not  separated  by  an  inter- 
trochlear  ridge.  The  fibula  has  not  been  found,  but  the 
tibia  shows  no  indication  of  its  having  been  fused  to  it. 

Ameghino  has  figured  the  astragulus  as  very  low,  with 
the  trochlea  flattened,  the  internal  condyle  being  wider 
and  flatter,  while  the  external  condyle  is  narrower  and 
somewhat  raised.  The  trochlea  is  peculiar  in  that  its 
proximal  margin  is  deeply  notched  by  a  depression  in  which 
there  is  a  large  perforation.  The  neck  is  prolonged  and 
carries  a  large  convex  head  articulating  with  the  navicular 
only.  The  measurements  given  are,  length  116  mm., 
width  75  mm. 

Gaudry  figures  a  calcaneum,  showing  a  long  narrow 
tuber,  and  the  facet  for  the  fibula  as  a  wide  shelf  which 
projects  strongly  on  the  external  side.  The  size  as  given 
by  Ameghino  is  240  mm.  long,  by  120  mm.  wide. 

I  have  two  associated  ungual  phalanges,  one  of  which 
corresponds  to  that  figured  by  Ameghino  as  the  third. 
It  is  high,  laterally  compressed,  has  a  very  rugose  surface 
on  either  side,  and  a  deep  cleft  in  the  end.  This  is  68  mm. 
long.  The  second  ungual  is  very  asymetrical,  also  laterally 
compressed,  and  with  the  point  curved  inward.  I  take  it 
to  be  the  fifth.  The  tibia,  the  tarsus,  and  the  phalanges 
strongly  suggest  that  this  animal  walked  on  the  side  of  its 
foot. 


140 


THE  DESEADO  FORMATION  OF  PATAGONIA 


Asmodeus  scotti  Ameghino 

A.  scotti  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  643. 
A.  scotti  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  477. 

This  species  is  not  represented  in  our  collection,  but  I 
reproduce  Ameghino's  figure  of  the  type,  and  of  the  milk 


Fig.   TOO.    Upper  and  lower  incisors,  canines,  and  premolars 
— 1/2  natural  size,  after  Ameghino. 


dentition.     Unfortunately  his  type  figure  is  from  the  side 
and  does  not  give  all  the  desired  information. 

In  the  upper  dentition,  the  small  incisors,  pitted  on  the 
crown,  increase  regularly  in  size  toward  the  rear;  and  each 
has  an  external  cingulum  around  the  base.  The  canine 
is  about  twice  the  size  of  the  adjacent  incisor,  and  also  has 


pm   '/ 


Fig.   101.  Milk  incisors,  canine,  and  premolars  and  permanent  m.  i  —  1/2 
natural  size,  after  Ameghino. 

an  external  cingulum.  The  premolars  increase  regularly 
in  size  and  also  have  at  least  an  external  cingulum.  Figure 
101  shows  a  dentition  which  Ameghino  described  as  the 
milk  set  of  A.  osborni.  At  the  same  time  he  remarks  the 
unusual  character  of  the  deciduous  canine  in  being  two- 
cusped.  I  think  this  set  of  teeth  should  be  interpreted  as 
deciduous  inc.  2  to  deciduous  pm.  4,  plus  the  permanent 


ASMODEUS  SCOTTI 


141 


molar  I.  With  such  an  interpretation,  we  find  the  incisors 
normal,  the  canine  normal  though  not  as  large  as  in  the 
permanent  set,  and  the  two-cusped  tooth  is  the  first  milk 
premolar.  The  last  tooth  in  the  series  is  considerably 
different  from  the  premolars  and  is  evidently  permanent 
molar  I ,  which  is  about  the  size  and  character  of  this  tooth 
in  A.  scotti,  much  too  small  to  belong  to  A.  osborni.  This 
set  of  milk  teeth  differ  from  the  permanent  teeth  in  that 
the  premolars  do  not  have  the  anterior,  inner  and  posterior 
cingulum,  characteristic  of  the  permanent  dentition. 

The  following  measurements  are  taken  from  Ameghino: 


Upper  dentition,  inc.  I  to  pm.  4 
Upper  dentition,  premolar  2,  length 
Upper  dentition,  premolar  3,  length 
Upper  dentition,  premolar  4,  length 
Upper  dentition,  molar  I,  length 
Upper  dentition,  molar  2,  length 
Upper  dentition,  molar  3,  length 


104  mm. 
18  mm.   width  25  mm. 


20  mm. 
23  mm. 
28  mm. 
37  mm. 
50  mm. 


width  28  mm. 

width  35  mm. 

width  39  mm. 

width  44  mm. 

width  48  mm. 


CHAPTER  XI 

ASTRAPOTHERIA 

THIS  group  is  composed  of  large,  long  limbed  creatures, 
with  a  highly  specialized  dentition,  in  which  the  canines 
of  the  upper  jaw  are  developed  into  great  curved  tushes, 
resembling  those  of  Pyr other ium;  while  the  canines  of  the 
lower  jaw  are  compressed  in  the  antero-posterior  diameter 
and  protrude  laterally,  like  those  of  pigs.  Upper  pre- 
molars  I  and  2  are  reduced  or  lacking,  while  pm.  3  and  4 
are  also  reduced,  but  usually  retained.  The  upper  molars 
are  brachydont,  and  have  a  crown  very  like  that  of  the 
molars  of  homalodontotheres. 

The  lower  incisors  are  small,  proclivious,  and  set  at 
intervals  around  the  broad  semicircle  of  the  front  of  the 
fused  lower  jaws.  The  lower  canines  are  permanently 
growing  teeth,  smaller  than  the  upper  canines,  project 
laterally,  and  have  the  tips  recurved.  Premolars  i  and 
2  are  usually  lacking,  pm.  3  more  or  less  reduced,  and  pm. 
4  is  a  normal,  short,  molariform  grinder.  The  lower 
molars  have  the  same  basal  pattern  as  in  Toxodonta, 
the  crown  carrying  two  crescents  with  a  plump  pillar  in 
the  basin  of  the  posterior  crescent,  the  pillar,  however, 
being  situated  far  forward  near  the  anterior  horn  of  the 
rear  crescent. 

Lydekker  made  an  order  Astrapotheria  including  the 
Astrapotheria  and  Homalodontotheria,  but  as  the  dentition 
of  the  two  groups  is  so  different,  because  of  the  enormous 
enlargement  of  the  frontal  region,  and  because  of  the 
reduction  of  the  premolars,  I  am  convinced  that  these 
two  groups  represent  totally  divergent  lines  of  develop- 
ment; and  I  have  therefore  made  each  of  the  groups  a 
separate  suborder. 


PARASTRAPOTHERIUM 


143 


Ameghino  has  described  several  genera,  which  make 
a  progressive  series  and  show  a  constantly  progressive 
variation  as  far  as  they  are  known. 


GENUS 
Albertogaudryi 


Astraponotus 


FORMATION 
Casamayor 


Astraponotus 


FORMULA 


-  Post,  inner  and  post, 
median,  cusps  isola- 
ted. 


?  i  ?  3 


3-    Post, 


nner  cusp,  un- 


ted with  wall  making 
small  lobe. 


Parastrapotherium     Deseado  and  Colpodon 

Astrapothericulus      Astrapothericulus 
Astrapotherium          Santa  Cruz 


?  *  2  3    Post,   lobe   large,   also 
23        a  strong  crista. 


?  i  2  3 


3123 

3123 
3113 


In  the  Deseado  beds,  beside  Par  astro  pother  turn,  Ame- 
ghino has  described  Liarthrus,  based  on  an  upper  second 
premolar  and  part  of  another  tooth,  but  I  can  see  no 
structural  variation  from  Parastropotherium  or  indeed  from 
P.  holmbergi;  so  I  consider  this  genus  as  a  synonym.  As 
to  the  genus  Traspoatherium,  I  can  not  see  in  it  any  reason 
for  making  a  genus  separate  from  Parastrapotherium. 

Parastrapotherium  Ameghino 

Parastrapotherium  Amegh.,  1895,  Bol.  Inst.  Ceog.  Argen.,  t.  15,  p.  636. 
Parastrapotherium  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  449. 
Liarthrus  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  641. 
Liarthrus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  451. 
Traspoatherium  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  641. 
Traspoatherium  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  450. 

The  genus,  in  general,  is  similar  to  Astrapotherium,  so 
that  Gaudry  considered  it  the  same,  but  Ameghino  has 
distinguished  it  by  the  tushes  being  relatively  of  smaller 
size,  the  lower  incisors  larger,  and  by  the  presence  of  pm.  3 


144  THE  DESEADO  FORMATION  OF  PATAGONIA 

in  the  lower  series.  The  Deseado  forms  are  also  of  con- 
siderably larger  size  than  the  Santa  Cruz. 

Our  material  includes  a  pair  of  lower  jaws,  two  scap- 
ulae, the  humerus,  and  the  lower  end  of  the  femur. 

No  skull  has  been  found  in  the  Deseado.  Those  from 
the  Santa  Cruz  are  enormously  swollen  over  the  orbits, 
the  massive  bone  making  a  skull  wholly  unique.  The 
lower  jaws  are  similar  to  those  of  Astrapotherium,  except 
that  the  rami  are  deeper.  The  front  ends  are  fused  and 
expanded  making  the  anterior  much  enlarged,  and  causing 
the  incisors  to  stand  at  intervals  as  in  Coryphodon.  The 
symphysis  is  massive  and  prolonged  backward  nearly  to 
premolar  3.  The  rami  are  plump  and  unusually  thick. 


Fig.  102.  Upper  dentition  of  Astrapothericulus  iheringi — 
1/2  natural  size. 

Of  the  upper  dentition,  Ameghino  figures  only  the  first 
molar  and  the  canine.  I  have  given  Ameghino's  figure 
of  the  upper  dentition  of  Astrapothericulus,  to  indicate 
what  this  would  be  like,  for  the  variation  is  only  slight. 
The  canine  is  a  great  tush,  not  unlike  the  incisor-tush  of 
Pyrotherium,  oval  in  cross  section  with  the  greater  diameter 
from  front  to  back.  The  first  and  second  premolars  have 
disappeared.  Premolars  3  and  4  are  greatly  reduced. 
The  molars  are  very  like  those  of  Asmodeus,  large  brachy- 
dont  grinders,  composed  of  an  outer  wall,  and  an  anterior 
and  posterior  lobe.  The  external  cingulum  is  a  trace 
only,  and  the  internal  cingulum  is  developed  in  varying 
degrees.  The  basin  is  deep  and  subdivided  by  a  crista 
which  rises  from  the  external  wall,  and  as  the  surface  is 
worn  off  unites  with  the  anterior  lobe,  cutting  off  a  small 


PARASTRAPOTHERIUM  145 

pit.  Behind  the  posterior  lobe  is  a  small  basin,  bounded 
in  the  rear  by  a  second  crista  from  the  rear  end  of  the 
external  wall,  which,  as  the  tooth  is  worn  down,  unites 
with  the  posterior  lobes,  cutting  off  a  small  posterior  pit, 
suggestive  of  that  of  homalodontotheres. 

The  three  lower  incisors  are  expanded  at  their  ends  into 
thick  shovel-like  crowns,  each  with  a  strong  crescentic 
cingulum  on  the  posterior  face,  and  with  a  shallow  furrow 
on  both  the  front  and  back  faces.  Relatively  the  incisors 
are  much  larger  and  longer  than  in  Astropotherium. 

The  lower  canine  is  flattened  on  the  upper  face,  so  that 
its  cross  section  is  close  to  semicircular  making  a  typical 
permanently  growing  rooting  implement.  This  tooth  is 
relatively  shorter  and  smaller  than  in  Astrapotherium. 

Premolars  I  and  2  are  wanting,  a  long  diastema  occupy- 
ing the  interval  between  the  canine  and  pm.  3.  Premolar 
3  is  greatly  reduced  in  size,  and  in  my  specimen  has  fallen 
out,  being  represented  by  a  small  alveolus.  I  judge  that 
in  old  individuals  it  falls  out.  The  fourth  premolar  and 
the  molars  are  typically  those  of  Toxodontia.  The  young 
show  two  plump  crescents,  with  a  low  plump  pillar,  sit- 
uated near  the  anterior  horn  of  the  posterior  crescent, 
which  pillar,  as  the  tooth  wears,  unites  with  the  anterior 
horn. 

The  scapula  is  a  remarkably  heavy  and  elongated  bone, 
greatly  arched  where  it  lay  over  the  ribs.  The  spine  is 
high  and  heavy,  with  the  upper  margin  developed  into 
a  thick  ridge  like  a  banister  rail,  which  is  prolonged  in 
front  to,  or  a  little  beyond,  the  level  of  the  glenoid  fossa, 
this  distal  portion  being  expanded  into  a  broad  plate  more 
than  half  as  wide  as  the  widest  portion  of  the  blade  of  the 
scapula.  The  glenoid  fossa  is  relatively  small,  oval  in 
outline,  and  with  the  long  axis  parallel  to  the  long  axis 
of  the  body.  The  anterior  margin  of  the  articular  surface 
is  reflexed,  apparently  to  come  in  contact  with  the  base  of 
the  greater  tuberosity  of  the  humerus.  This  glenoid  cavity 


146  THE  DESEADO  FORMATION  OF  PATAGONIA 

is  only  large  enough  to  actually  eover  about  half  of  the  head 
of  the  humerus,  and  fits  so  that,  in  a  position  of  rest,  the 
glenoid  covered  the  outer  part  of  the  humeral  head,  and 
only  articulated  on  the  inner  part  of  the  humerus  head 
when  the  limb  was  bent  inward.  The  blade  of  the  scapula 
is  narrow,  with  the  proximal  end  prolonged  and  ending 
in  a  thick  rugose  mass.  The  anterior  and  posterior  mar- 
gins are  rugose  and  thickened,  the  great  thickness  of  the 
proximal  end  being  due  to  the  convergence  of  these  thick- 
ened margins  and  the  heavy  spine.  Lastly,  this  thick 
proximal  end  is  peculiar  in  having  on  its  posterior  side  a 
large  rugose  cavity,  which  was  apparently  to  receive  mus- 
cular attachments. 

For  such  a  heavy  animal,  the  humerus  is  extraordinarily 
long  and  slender.  The  sessile  head  is  strongly  compressed 
from  side  to  side,  very  convex,  and  much  larger  than  the 
glenoid  fossa,  its  articular  surface  extending  onto  the  base 
of  the  greater  tuberosity.  This  tuberosity  is  heavy  and 
thick,  but  does  not  project  above  the  head.  The  powerful 
deltoid  ridge  extends  from  the  tuberosity  two-thirds  of 
the  way  down  the  shaft.  The  shaft  is  unusually  slender. 
Distally  it  expands  laterally  to  make  the  two  large  epicon- 
dyles,  of  nearly  equal  size.  The  trochlca  is  relatively 
narrow,  the  internal  surface  being  the  narrower,  and  rising 
to  a  high  margin;  while  the  external  portion  is  wider, 
rounded,  and  has  a  low  margin.  The  supratrochlear 
fossa  is  moderately  deep,  the  anconeal  fossa  somewhat 
deeper,  but  there  is  no  connecting  foramen. 

Gaudry*  figures  a  radius  and  ulna,  both  relatively  long 
bones,  and  closely  apposed;  so  that  there  was  no  possibility 
of  a  rotary  motion  of  the  forearm.  The  proximal  end 
of  the  radius  is  expanded,  so  that  its  articular  surface 
is  in  contact  with  the  full  width  of  the  humeral  trochlea 
on  the  anterior  side.  Below,  the  bone  contracts  to  a 
moderately  slender  shaft,  and  then  expands  distally  into 

*Anal.  Palacontologic,  t.  I,  p.  5,  1906. 


PARASTRAPOTHERIUM  147 

a  heavy  club-like  distal  end.  The  ulna  has  a  short  but 
heavy  olecranon  process,  with  a  prominent  coronoid 
process.  The  sigmoicl  notch  is  shallow,  but  the  articular 
surface  expands  on  both  sides,  so  that  it  covers  the  full 
width  of  the  humeral  trochlea  on  the  posterior  side.  Dis- 
tally  the  ulna  is  not  so  heavy  as  the  radius. 

Under  the  name  Pyrotherium  romeri,  Ameghino*  figures 
a  carpus  and  metacarpus,  which  Tournierf  however  assigns 
to  Parastrapotherium,  probably  P.  herculeum;  and  figures 
a  carpus  and  metacarpus  of  the  same  type,  but  smaller, 
which  he  attributes  to  Parastrapotherium.  I,  however, 
can  not  see  how  such  a  small  foot  can  belong  to  so  large 
an  animal,  and  feel  that,  until  evidence  of  direct  association 
is  given,  it  is  best  not  to  consider  these  feet  as  belonging 
to  Parastrapotherium,  but  rather  to  Pyrotherium. 

Of  the  femur  I  have  only  the  distal  end,  which,  however, 
corresponds  completely  with  the  one  figured  by  Gaudry. 
It  is  a  long  bone,  slightly  shorter  than  the  humerus,  with 
a  small  head,  set  on  a  short  and  poorly  outlined  neck. 
The  greater  trochanter  is  wide  and  rugose,  rising  to  about 
the  same  height  as  the  head.  The  lesser  trochanter  is 
not  distinguishable.  About  the  middle  of  the  shaft  there 
is  a  powerful  third  trochanter,  which  continues  as  a  narrow 
ridge  upward  to  the  greater  trochanter,  and  downward 
in  a  similar  narrow  ridge  almost  to  the  outer  condyle. 
At  the  proximal  end  the  shaft  is  greatly  flattened,  but  in 
the  central  and  lower  parts  becomes  almost  circular  in 
section.  The  two  condyles  are  set  wide  apart,  project 
considerably  behind  the  posterior  face  of  the  shaft,  and 
and  are  only  slightly  convex.  The  trochlea  is  of  moderate 
width,  short,  and  shallow. 

Gaudry  outlines  a  short,  heavy,  rugose  calcaneum  which 
has  but  a  short  tuber;  a  flat  navicular;  a  small  cuboid; 
and  an  astragulus  with  only  a  slight  convexity  of  the 

*  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  442,  fig.  25,  1897. 
t  Bui.  Soc.  Geol.  France,  ser.  4,  t.  5,  p.  305,  1905. 


148 


THE  DESEADO  FORMATION  OF  PATAGONIA 


trochlea,  and  with  the  navicular  facet  directed  obliquely 
forward,  making  an  angle  of  127°  with  the  plane  of  the 
trochlea,  which,  as  he  says,  would  indicate  a  semidigiti- 
grade  position  of  the  pes. 

The  following  species  are  distinguished  by  Ameghino 
as  coming  from  the  Deseado  beds:  P.  holmbergi,  P.  Irons- 
sarti,  P.  lemoinei,  P.  ephebicum,  P.  martiale,  P.  super abile, 
P.  insuperabile.  The  various  species  are  known  from 
the  same  parts  in  but  a  few  cases.  Their  relative  sizes 
are  indicated  from  the  following  compilation  of  the  measure- 
ments given  by  Ameghino: 


UPPER 

LOWER 

LOWER 

LOWER 

pm.  4 

m.  i 

m.  2 

m.  3 

pm.  4 

m.  i 

m.  2 

m.  3 

inc.  r 
-m.  3 

pm.  4 
-m.  3 

P.  holmbergi 

56-56 

P.  troussarti 

24- 

40- 

57- 

60- 

180 

P.  lemoinei 

34-34 

P.  ephebicum 

31-16 

42-21 

P.  martiale 

30-42 

82-83 

550 

P.  superabile 

30-43 

P.  insuperabile 

37-48 

100-80 

34-23 

P.  (Liarthrus)  co- 
pei 

29-46 

P.      (Traspoathe- 
rium)    convexi- 
dens 

19-27 

Amherst  specimen 

28-26 

43-28 

58-32 

70-36      455 

200 

P.  holmbergi  is  the  type  species,  and  of  considerable  size, 
and  to  it  I  have  assigned  my  material.  In  such  a  large 
animal,  variations  in  size  are  to  be  expected.  P.  troussarti, 
as  described,  is  a  tenth  smaller  than  P.  holmbergi,  the  only 
structural  character  differentiating  it  being  the  isolation 


PARASTRAPOTHERIUM  149 

of  the  pillar  in  the  lower  molars,  which  is  a  character 
due  to  youth;  so  I  have  considered  it  a  synonym  of  P. 
holmbergi.  P.  ephebicum  is  a  much  smaller  and  distinct 
species,  with  which  I  should  associate  the  single  upper 
molar  to  which  the  name  P.  lemoinei  has  been  given. 
P.  martiale  is  a  large  species,  distinguished  by  the  strong 
development  of  the  cingulum  on  the  internal  side  of  the 
upper  molars,  and  on  the  inner  side  of  the  lower  molars; 
and  by  lower  premolar  3  being  well  developed  with  two 
roots.  P.  superabile  is  of  the  same  size  as  the  foregoing, 
but  has  the  cingulum  on  upper  premolar  4  (the  only  tooth 
known)  less  developed.  I  should  therefore  consider  it  a 
synonym  of  P.  martiale.  P.  insuperabile  is  the  largest 
species,  and  is  distinguished  by  the  excessive  development 
of  the  cingulum.  Liarthrus  is  founded  on  an  upper  pm.  4 
with  a  part  of  pm.  3,  but,  as  far  as  I  can  see,  does  not  differ 
in  character  or  size  from  P.  holmbergi.  Traspoatherium 
is  based  on  upper  premolars  which  are  distinguished  by 
the  roots  being  fused  from  side  to  side.  I  think  it  is  an 
age  character  and  for  the  present  would  consider  it  the 

same  as  P.  holmbergi,  probably  the  tooth  being  pm.  3. 

/ 

Parastrapotherium  holmbergi  Ameghino 

P.  holmbergi  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  636. 
P.  holmbergi  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  449. 
P.  troussarti  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  638. 
P.  troussarti  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  449. 
Liarthrus  copei  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  641. 
Liarthrus  copei  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  451. 
Traspoatherium  convexidens  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p. 

641. 
Traspoatherium  convexidens  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p. 

450. 
Parastrapotherium  holmbergi  Tournier,  1905,  Bui.  Soc.  Geol.   France,   ser.  4, 

t.  5,  P.  305. 
Astrapotherium  holmbergi  Gaudry,  1906,  Anal.  Palaeontologie,  t.  I,  p.  5. 

To  this,  the  type  species,  I  have  assigned  all  the  material 
we  found  on  the  Chico  del  Chubut,  west  of  Puerto  Visser, 


150  THE  DESEADO  FORMATION  OF  PATAGONIA 

as  enumerated  under  the  generic  description.  The  lower 
jaws  belonged  to  an  old  individual.  The  humerus  and 
scapulae  were  found  associated,  the  femur  isolated. 

Of  the  upper  dentition,  the  only  available  measurements 
are  those  of  Ameghino  for  the  first  molar,  and  the  canine. 

Upper  dentition,  canine,  length  256  mm. 

Upper  dentition,  molar  I,  length  57  mm.,  width         57   mm. 


Fig.  103.  Upper  molar  i  of  the  left  side — natural  size, 
al'trr  Ameghino. 

The  measurements  of  the  complete  pair  of  lower  jaws 
which  we  found  are 

Lower  dentition,  length  from  inc.  I  to  m.  3  455  mm. 

Lower  dentition,  incisor  2,  length  22  mm.,  width  22  mm. 

Lower  dentition,  canine,  ant.  post.  diam.  at  alveolus  52  mm. 

Lower  dentition,  canine,  trans,  diam.  at  alveolus  26  mm. 

Lower  dentition,  diastema  from  c.  to  pm.  3  116  mm. 

Lower  dentition,  premolar  4,  length  28  mm.,  width  26  mm. 

Lower  dentition,  molar  I,  length  43  mm.,  width  28  mm. 

Lower  dentition,  molar  2,  length  58  mm.,  width  32  mm. 

Lower  dentition,  molar  3,  length  70  mm.,  widlh  36  mm. 

Height  of  mandible  under  molar  3  83  mm. 

The  scapula  is  a  very  long  heavy  bone,  with  a  narrow 
blade,  and  a  high  spine  which  has  its  upper  margin  thick- 
ened so  as  to  appear  like  a  banister  rail.  We  found  one 
complete  scapula  and  a  second  incomplete  one  associated 
with  it,  which  corresponded  in  all  ways  to  the  first  one. 


PARASTRAPOTHERIUM  HOLMBERGI 


Fig.   104.  Lower  jaws — 1/5  natural  size. 


Fig.  105.  Dorsal  view  of  right  scapula — 1/5  natural  size. 


152  THE  DESEADO  FORMATION  OF  PATAGONIA 


Fig.   106.  Right  humerus,  posterior  aspect — 
i/5  natural  size. 


Fig.  107.  Left  femur,  posterior  side — 1/5 
natural  size;  outline  of  upper  portion  after 
Gaudry  from  Astrapotherium  magnum. 


PARASTRAPOTHERIUM  HOLMBERGI  153 

The   following   measurements   are    taken   from   specimen 
No.  3328: 

Scapula,  greatest  length  694  mm. 

Scapula,  greatest  width  283  mm. 

Scapula,  glenoid  fossa,  ant. -post,  diameter  130  mm. 

Scapula,  glenoid  fossa,  transverse  diameter  90  mm. 

Scapula,  height  of  spine  120  mm. 

Scapula,  width  of  enlarged  margin  of  spine  at  the  lower  end  170  mm. 

Scapula,  width  of  margin  in  middle  45  mm. 

The  humerus  was  associated  with  the  two  scapulae 
mentioned  above,  and  is  complete.  For  such  a  large 
animal,  its  length  is  excessive,  greater  than  that  of  the 
species  assigned  by  Gaudry  to  P.  herculeum  which  species 
has  a  skull  larger  than  that  of  P.  holmbergi. 

Humerus,  greatest  length  720  mm. 

Humerus,  greatest  width  across  proximal  end  248  mm. 

Humerus,  least  diameter  of  shaft  78  mm. 

Humerus,  width  across  the  epicondyles  220  mm. 

Humerus,  width  of  trochlea  on  distal  end  125  mm. 

The  femur  which  Gaudry  figures  as  belonging  to  Astra- 
potherium  magnum  corresponds,  as  far  as  the  distal  end 
will  admit  comparison,  with  the  one  which  we  found  in 
the  Deseado  beds,  so  that  in  restoring  the  outline  of  the 
missing  parts,  I  have  based  it  on  this  A.  magnum. 

Femur,  length  (estimated)  48°  mm- 

Femur,  width  of  distal  end  135  mm- 

Femur,  width  of  trochlea  57  mm- 

Parastrapotherium  ephebicum  Ameghino 

P.  ephebicum  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  639. 
P.  ephebicum  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  449. 
P.  lemoinei  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  640. 
P.  lemoinei  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  450. 
Astrapotherium  ephebicum  Gaudry,  1904,  Mem.  Soc.  Geol.  France,  t.  12,  p.  15. 

Ameghino  based  this  species  on  a  portion  of  the  mandible 
of  an  old  individual  with  molars  I  and  2.  Its  chief  dis- 
tinction lies  in  its  small  size  as  compared  with  P.  holmbergi. 
Gaudry  assigned  to  this  species  some  upper  teeth.  We 


154 


THE  DESEADO  FORMATION  OF  PATAGONIA 


found  no  specimens  of  this  species.     The  following  are 
the  measurements  of  the  type  according  to  Ameghino. 


Lower  dentition,  molar  I,  length 
Lower  dentition,  molar  2,  length 


31   mm.,  width    16  mm. 
42  mm.,  width    21    mm, 


Parastrapotherium  martiale  Ameghino: 

P.  martiale  Amegh.,  1901,  Bol.  Acad.  Nac.  Cordoba,  t.  16,  p.  402. 
P.  superablie  Amegh.,  1901,  Bol.  Acad.  Nac.  Cordoba,  t.  16,  p.  402. 

The  species  seems  to  have  been  founded  on  abundant 
material,  representing  an  animal  of  larger  size    than  P. 

holmbergi,  which  is  dis- 
tinguished  by  the 
greater  width  of  the 
crowns  of  the  incisors, 
by  straight  canines 
diverging  but  little,  by 
a  strong  cingulum  on 
the  outer  side  of  the 
lower  molars  and  the 
inner  side  of  the  upper 
molars,  and  by  the 
narrow  symphysis  of 
the  lower  jaws.  P. 
superabile  was  distinguished  by  a  difference  in  the  arrange- 
ment of  the  roots  of  upper  pm.  4,  but  as  the  pattern  of  the 
crown  is  the  same,  as  is  also  the  size,  I  feel  that  this  differ- 
ence is  simply  an  individual  variation.  The  following 
measurements  are  given  by  Ameghino: 


Fig.  1 08.    Upper  molar  i  of  the  left  side 
after  Ameghino. 


-natural  size, 


Upper  dentition,  length  from  pm.  3  to  m.  3 

Uppt-r  dentition,  premolar  4,  length 

Upper  dentition,  premolar  4,  width 

Upper  dentition,  molar  2,  length 

Upper  dentition,  molar  2,  width 

Lower  dentition,  length  from  inc.  I  to  m.  3 


240  mm . 
30  mm. 
43  mm, 

82  mm. 

83  mm. 
550  mm. 


PARASTRAPOTHERIUM  1 55 

Paras trapotherium  insuperabile  Ameghino 

P.  insuperabile  Amegh.,  1901,  Bol.  Acad.  Nac.  Cordoba,  t.  16,  p.  403. 

This  is  the  largest  of  all  the  species,  and  is  distinguished 
by  the  enormous  development  of  the  cingulum  on  the 
anterior,  inner,  and  posterior  sides  of  the  upper  molars, 
the  same  being  uninterrupted  and  so  elevated,  that  the 
internal  crests  seem  to  rise  out  of  a  basin.  The  following 
measurements  are  taken  from  Ameghino: 

Upper  dentition,  premolar  4,  length  37  mm.,  width    48  mm. 

Upper  dentition,  molar  3,  length  100  mm.,  width    80  mm. 

Lower  dentition,  premolar  4,  length  43  mm.,  width    23  mm. 


CHAPTER  XII 
PROBOSCIDEA 

Suborder  Pyrotheria 

THIS  suborder  was  established  by  Ameghino  to  receive 
the  peculiar  genus  Pyrotherium  and  related  forms.  These 
animals  are  of  large  size,  massive  build,  with  narrow 
elongated  skulls,  in  which  the  nasal  opening  is  situated 
far  back,  as  in  animals  with  a  proboscis;  with  a  tiny  brain 
case  surrounded  by  cellular  spaces;  with  the  maxillae, 
palatines,  pterygoids  and  alispenoids  developed  downward, 
so  that  the  palatal  plane  makes  a  strong  angle  with  the 
basi-cranial  plane;  and  with  the  occipital  condyles  high 
up  on  the  back  of  the  skull.  Then  the  first  and  second 
upper  incisors  and  the  second  lower  incisors  are  developed 
into  enormous  tushes  with  enamel  on  the  anterior  sides  only. 
The  remaining  incisors,  the  canines,  upper  premolar  i, 
and  lower  premolars  I  and  2  are  wanting;  the  remaining 
premolars  and  the  molars  being  developed  into  great 
quadrilateral  grinders,  each  with  two  transverse  crests. 
The  neck  is  short,  the  limbs  massive  and  short,  especially 
the  lower  members  of  each  limb,  and  the  feet  were  probably 
five- toed. 

The  relationship  of  these  forms  has  been  the  subject 
of  extended  discussion:  Ameghino  seeing  in  this  genus 
the  ancestors  of  the  Probiscidea,  and  comparing  them  with 
Palaeomastodon,  Dinotherium  and  Barytherium,  even  finding 
resemblances  to  Diprotodon;  Gaudry  concludes  that  they 
are  not  proboscidians;  and  others  have  suggested  that 
they  were  specialized  toxodonts.  I  have  prepared  the 
following  table  of  comparisons  with  Palaeomastodon,  a 
toxodont,  and  Diprotodon. 


PYROTHERIUM 


157 


PYROTHERIUM 

PALAEOMASTODON 

TOXODONT, 
NESODON 

DlPROTODON 

2 

Upper  tush 

Inc.  i  enlarged 
Inc.  2  tush 

Inc.  i  enlarged  in 
Moeritherium. 
Inc.  2  tush 

Inc.  i  reduced 
Inc.  2  caniniform 
tush 

Inc.  i  tush 
Inc.  2  reduced 

Upper  molars 

Bilophodont 

Bilophodont    in 
Mastodon  and 
Dinotherium 

Rhinoceros-like 

Bilophodont 

3 

Lower  tush 

Inc.  2  (?) 

Inc.  2 

Inc.  3 

Inc.  i 

4 

5 

6 

Lower  molars 

Bilophodont 

Bilophodont      in 
Mastodon  and 
Dinotherium 

Bicrescentric 

Bilophodont 

Nasal  opening 

Over  molar  i 

Over  molar  i 

Over  incisors 

Over  diastema 

Basicranial  axis 

Plane  of  base  of 
cranium  bent  up, 
makes  140°  with 
plane  of  palate 

Plane   of  base   of 
cranium  bent  up, 
makes  155°  with 
plane  of  palate 

Plane    of  base  of 
cranium  parallel 
with    plane    of 
palate 

Plane   of  base   of 
cranium  parallel 
with     plane    of 
palate 

7 

Pterygoids 

Pterygoids  plus 
alisphenoids 
make  great  verti- 
cal plates 

Pefcrygoids       plus 
alisphenoids 
make  great  verti- 
cal plates 

Pterygoids  normal 

Pterygoids  normal 

8 

Jugal 

Takes  small  part 
on  glenoid  fossa 

Takes  small   part 
on  glenoid  fossa 

Takes  no  part  on 
glenoid  fossa 

Extends  to  glenoid 
fossa 

9 

Posttympanic  process  of 
squamosum 

Surrounds  meatus, 
and  crowds  out 
tympanic 

Surrounds  meatus 
and    crowds   out 
tympanic 

Surrounds  meatus 
and   crowds   out 
tympanic 

Not  surround  me- 
atus   nor    crowd 
out  tympanic 

10 

Tympanic  bulla 

Small,  inflated, 
hollow 

Small,  inflated, 
hollow 

Large,  i  n  fla  ted, 
hollow 

n 

Palatine  bones 

Narrow  in  front, 
expanding  behind 

Narrow   in   front, 
expanding  behind 

Wide  in  front,  nar- 
rowing somewhat 
behind 

13 

Premaxilla 

Crowded  out  from 
forming  any  por- 
tion of  palate 

Crowded  out  from 
forming  any  por- 
tion of  palate 

Makes     front     of 
palate 

Fused  to  maxilla 

13 

14 

Antorbital  foramen 

2  foramena 

2  foramena 

i  foramen 

i  foramen 

Intercellular  laminae 

Present 

Present 

None 

None 

15 

Atlas 

Long,  has  hypo- 
physis 

Long,    has    hypo- 
physis 

Long,     no     hypo- 
physis 

Short,    no     hypo- 
physis 

16 

Axis 

Hemispherical 
odontoid 

Rounded  odontoid 

Peg  like  odontoid 

Odontoid    slightly 
flattened  on  top 

158 


THE  DESEADO  FORMATION  OF  PATAGONIA 


PYROTHERIUM 

PALAEOMA  STODON 

TOXODONT, 
NESODON 

DIPROTODON 

Cervicals  3-7 

Very  short 

Very  short 

Moderately  long 

Short 

Humerus 

Flattened  deltoid 
ridge  with  post, 
spur 

Flattened    deltoid 
ridge  with   post, 
spur 

Rounded  no  spur 
on  deltoid  ridge 

Flattened  distally, 
tiny  spur  on  del- 
toid ridge 

Radius  and  Ulna 

Very  short  and 
massive 

Moderate  length 

Fairly  long 

Femur 

Flattened,  Gr.  tro- 
chanter  low,  no 
3rd  trochanter 

Flattened,  Gr.  tro- 
chanter low,  trace 
of  3rd  trochanter 

Rounded,  Gr.  tro- 
chanter high,  3rd 
trochanter 

Rounded,  Gr.  tro- 
chanter very  low, 
no  3rd  trochanter 

Tibia 

Short  and  massive, 
free  from  fibula 

Short  and  massive, 
free  from  fibula 

Moderate  length, 
fused  to  fibula  at 
upper  end 

Moderate  length, 
free  from  fibula 

Still  other  forms  like  Amblypoda  and  Arsinotherium  have 
been  suggested  as  having  characters  in  common  with 
Pyrotherium,  and  it  is  clear  that,  with  such  a  variety  of 
forms,  some  of  the  characters  must  be  parallelisms  due 
to  a  common  adaptation,  and  only  one  of  these  varied 
groups  can  be  the  one  to  which  Pyrotherium  is  related. 
For  myself,  I  have  made  comparisons  with  the  Amblypoda 
and  Arsinotherium,  and  feel  that  such  features  as  the  mas- 
sive limbs,  shape  of  individual  bones,  etc.,  are  due  simply 
to  the  fact  that  all  these  are  massive  animals.  In  the 
case  of  Arsinotherium,  there  are  some  characters  which 
are  also  common  to  hyracoids  and  elephants,  like  the 
position  of  various  basicranial  foramena,  the  prolongation 
backward  of  the  jugal  and  the  shape  of  the  palatines. 
My  conclusion  is  that  Pyrotherium  is  related  to  the  pro- 
boscideans, and  came  from  the  same  stock  which  gave 
rise  to  hyracoids,  elephants  and  Arsinotherium.  I  think 
further  that  Pyrotherium  belongs  definitely  to  the  pro- 
boscidean line. 

Referring  back  to  the  foregoing  table.  The  develop- 
ment of  tushes  may  be  an  adaptive  character;  but  in  the 
elepnants  it  is  inc.  2  of  the  upper  and  inc.  2  of  the  lower 


PYROTHERIUM  159 

jaw  which  are  so  developed.  In  Pyrotherium,  in  the  upper 
dentition,  it  is  also  inc.  2  which  makes  the  tush,  and  inc.  I 
is  enlarged  as  in  Moeritherium,  and,  so  far  as  we  know, 
has  not  been  reduced  in  later  forms  as  it  was  in  the  elephant 
line.  In  the  lower  jaw  we  have  no  final  evidence  which 
will  show  whether  it  is  inc.  I  or  inc.  2  which  makes  the 
tush;  but  the  lower  tush  bites  against  upper  inc.  2  and  I 
have  considered  it  to  be  incisor  2. 

The  loss  of  the  teeth  behind  the  tushes  is  a  character 
to  be  expected  in  the  development  of  tushes  and  gives  no 
data.  The  bilophodont  character  of  the  back  teeth  has  oc- 
curred many  times  in  the  animal  kingdom  and  while  it 
may  be  the  inheritance  of  the  early  elephants  it  can  not 
be  used  as  an  argument. 

The  position  of  the  nasal  opening  looks  very  much  like 
that  of  elephants,  but  again  is  coincident  with  the  devel- 
opment of  a  proboscis.  However,  this  has  not  occurred 
a  great  number  of  times  in  the  animal  kingdom,  and  where 
it  has,  it  takes  a  variety  of  forms  of  modification.  In  Py- 
rotherium, the  modification  is  of  the  type  in  elephants,  and 
elephants  only. 

A  very  striking  feature  is  the  development  of  the  dental 
region  downward  so  that  the  basi-cranial  axis  is  bent 
upward,  makmg  an  angle  of  about  140  degrees.  There 
are  other  cases  of  the  bending  of  the  basicranial  axis; 
but  in  the  other  ungulates  it  is  a  bend  downward,  the 
reverse  of  what  we  find  here  and  in  elephants.  To  adjust 
the  posterior  part  of  the  nasal  chamber  to  this,  the  ptery- 
goids  and  the  alisphenoids  are  developed  into  great  wing- 
like  plates  on  either  side.  I  find  this  modification  of  the 
basicranial  axis  and  of  the  palatal,  pterygoid  and  alis- 
phenoid  bones  in  no  other  group  but  the  elephants.  In 
Palaeomastodon  it  has  been  developed  to  a  degree  so  that 
the  angle  is  about  155  degrees. 

The  back  of  the  palatine  bones  is  also  characteristic, 
for  the^e  begin  as  narrow  pointed  bones  and  behind  the 


1 60  THE  DESEADO  FORMATION  OF  PATAGONIA 

last  molar  expand  into  wide  plates,  just  as  in  Palaeomas- 
todon  (and  in  no  other  groups),  having  the  postpalatine 
foramen  opposite  or  behind  the  last  molar. 

The  posttympanic  region  of  the  squamosum  is  modified 
so  that  this  process  unites  with  the  anterior  squamosal 
region  to  crowd  out  more  or  less  completely  the  tympanic 
bone  where  it  should  surround  the  auditory  meatus. 
This  feature  is  common  to  the  elephants,  the  hyracoids,  and 
the  toxodonts,  so  that  I  consider  it  a  primitive  feature 
indicative  of  the  ultimate  common  ancestry  of  these 
groups.  The  tympanic  bulla  can  be  compared  with  that 
of  elephants  closely,  and  has  much  in  common  with  that 
of  toxodonts,  but  in  this  last  group  the  tympanic  is  much 
more  highly  developed. 

The  premaxilla  bone  in  Pyrotherium  is  crowded  out, 
so  that  it  makes  no  part  of  the  palate,  which  is  a  character 
of  elephants,  and  in  contrast  to  toxodonts  or  other  groups 
which  have  been  mentioned.  There  are  two  antorbital 
openings  as  in  elephants,  and  a  feature  not  common, 
though  not  unknown.  On  either  side  of  the  brain  case 
are  cellular  spaces  with  intercellular  lamellae,  which  are  so 
characteristic  of  elephants;  a  confirmatory  feature,  though 
in  itself  not  conclusive. 

The  foramena  on  the  base  of  the  cranium  are  similar 
to  those  on  the  base  of  the  cranium  of  elephants,  though 
there  are  some  variations,  as  for  instance,  the  exoccipital 
foramen,  is  isolated  in  Pyrollierium,  but  fused  with  the 
posterior  lacerum  foramen  in  elephants,  and  other  slight 
variations  in  position;  but,  on  the  whole,  the  foramena 
of  Pyrolherium  are  much  closer  to  those  of  elephants  than 
of  any  other  group.  There  is  also  much  in  common 
with  toxodonts  and  with  hyracoids,  as  would  be  expected 
if  they  have  a  common  ancestry.  There  is  no  suggestion 
of  a  marsupial  arrangement  as  would  be  necessary  if  related 
to  Diprotodon. 


PYROTHERIUM  l6l 

The  atlas  of  Pyrotherium  is  peculiar  in  having  a  marked 
hypophysis  which  is  unusual,  but  is  a  feature  of  the  atlas 
of  Palaeomastodon  and  Moeritherium.  The  axis  is  peculiar 
in  that  the  odontoid  is  flattened  on  the  upper  side  and 
very  short  and  wide.  In  this  the  form  is  unique.  The 
continuation  of  the  articular  surface  on  the  lower  sicle  of 
the  odontoid  with  the  articular  surfaces  of  the  ant.  cotyles 
is  a  feature  also  of  elephants.  The  remaining  cervicals 
are  greatly  shortened  almost  to  plates,  which  is  elephantine 
again,  though  this  short  neck  is  approximated  by  Dipro- 
todon,  some  Amblypods  and  Arsinotherium,  so  that  it 
must  be  in  general  looked  upon  as  an  adaptive  feature, 
though  in  its  detail  it  shows  again  an  elephant  character. 

The  upper  members  of  the  limbs  are  longer  than  the 
lower,  which  is  common  to  many  massive  animals.  The 
humerus  is  tremendously  flattened  from  front  to  back, 
even  more  so  than  in  any  of  the  animals  used  for  compari- 
son, though  flattening  is  a  feature  of  them  and  of  the 
elephants  the  most  so.  With  the  flattening,  the  deltoid 
ridge  is  prolonged  enormously  making  a  crest  along  the 
outer  side  of  the  bone,  which  at  the  lower  end  rises  in  a 
prominent  process,  as  in  elephants  (also  in  Diprotodon 
but  in  this  case  the  rest  of  the  bone  is  very  different). 
In  addition  to  this,  the  supinator  ridge  is  prolonged  up- 
ward until  it  almost  meets  the  deltoid,  ending  in  a  sharp 
spur  at  the  top.  This  spur  is  more  marked  in  Pyrotherium 
than  in  elephants,  although  they  show  the  same  develop- 
ment of  the  supinator  ridge. 

The  femur  has  the  head  much  higher  than  the  greater 
trochanter,  which  is  a  feature  common  to  elephants, 
Diprotodon,  Arsinotherium,  etc.,  so  that  it  must  be  looked 
upon  as  an  adaptation.  The  third  trochanter  has  disap- 
peared, and  in  elephants,  it  is  lost  in  the  advanced  forms, 
remaining  however  as  a  trace  in  Palaeomastodon. 

The  tibia  is  very  short  and  massive  and  hardly  gives 
any  suggestions  of  relationship,  except  that  it  is  not  fused 


1 62  THE  DESEADO  FORMATION  OF  PATAGONIA 

with  the  fibula  at  the  upper  end,  in  which  it  is  in  strong 
contrast  to  the  toxodonts. 

While  in  the  table  of  comparisons  numbers  I,  2,  3,  4, 
8,  9,  10,  14,  17,  19,  20,  and  21  may  be,  in  part,  or  wholly, 
interpreted  as  adaptations,  and  alone  would  not  be  at 
all  conclusive  of  relationship  to  elephants,  numbers  I,  5, 
6,  7,  8, n,  12,  13,  15,  18,  and  21  point  toward  the  elephants 
as  the  close  relatives  of  the  Pyrotheria.  In  the  first  series 
of  points  there  are  none  which  mitigate  against  associating 
these  two  groups,  while  if  the  attempt  is  made  to  associate 
Pyrotherium  with  any  group  other  than  Proboscidea  there 
are  strong  points,  and  a  number  of  them,  which  would 
prevent  this  association.  As  a  result  of  the  foregoing, 
together  with  a  feeling  which  continued  handling  of  the 
specimens  has  given  me,  I  can  come  to  no  other  conclusion 
than  that  the  Pyrotheria  should  be  placed  under  Probos- 
cidea. 

In  his  Linea  Filogenetica  de  los  Proboscideos,  Ameghino 
assigns  to  this  suborder,  or  at  least  puts  into  the  phylo- 
genetic  tree,  a  considerable  number  of  forms  from  the 
Casamayor  beds,  all  of  them  genera  with  bunodont  mo- 
lars, usually  known  by  but  one  or  two  teeth,  such  as  Asmith- 
woodwardi,  Nephracodus,  Cephanodus,  Paulo  gervaisia,  and 
the  better  known  genera,  Carlo  ameghinia,  and  Dido- 
lodus,  all  of  which  he  makes  ancestral  to  Pyrotherium. 
So  far  as  known,  however,  these  forms  show  none  of  the 
peculiarities  of  the  Pyrotherium  skull  or  dentition,  so  that 
it  is  difficult  for  me  to  see  any  reason  for  including  them 
even  in  the  suborder.  The  genus  Carlozittelia,  from  the 
upper  Casamayor,  is  in  a  different  position,  having  an 
enlarged  upper  incisor  (found  isolated)  and  molars  of  the 
bilophodont  type.  I  should  include  this  in  the  family 
Pyrotheridae  and  none  of  the  others. 


PYROTHERIUM  163 

Pyrotheriidae  Ameghino 

All  the  forms  assigned  to  this  family  are  supposed  to  be 
closely  related  to  Pyrotherium  and  to  have  much  the  same 
structure.  Ameghino  has  proposed  the  following  genera, 
Pyrotherium,  Parapyr  other  ium,  Richardowenia,  Archaeolo- 
phus,  Propyr other ium. 

Parapyr other ium  is  based  on  a  small  molar  and  a  tush 
which  Ameghino  first  described  as  Pyrotherium  planum, 
later  elevating  the  species  to  a  genus,  designated  as  Para- 
pyrotherium,  differentiated  by  the  transverse  crests  being 
low  and  the  valley  at  either  end  being  blocked  by  an 
intertubercular  ridge.  Gaudry  considered  that  this  genus 
represented  either  the  milk  teeth  of  P.  romeri,  or  a  variation 
of  that  species.  I  can  not  see  the  basis  of  a  new  genus  in 
the  material. 

The  genus  Richardoweni  is  based  on  half  of  a  molar, 
which  has  the  transverse  crest  interrupted  in  the  middle. 
Too  little  is  known  of  this  form  to  base  a  valid  genus  or 
even  to  associate  it  with  Pyrotherium. 

Archaeolophus  is  founded  on  a  small  tush  and  part  of 
an  upper  molar,  also  inadequate  material  for  a  genus. 
It  is  probably  Pyrotherium. 

Pro  Pyrotherium  is  a  smaller  form  from  the  Astraponotus 
beds,  apparently  a  good  genus;  the  type  species  being 
P.  saxeum,  of  considerable  smaller  size  than  any  of  the 
Deseado  species.  The  distinctive  features  of  the  genus 
can  not  be  given  until  more  material  is  known. 

Carlozitteli  is  based  on  a  small  form  from  the  Casamayor 
with  narrow  molars.  An  incisifoVm  tush  is  associated  with 
the  molar,  which,  if  correctly  associated,  would  indicate 
a  wide  deviation  from  Pyrotherium,  and  would  probably 
be  an  ancestral  form.  A  second  species  is  reported  from 
the  lower  Deseado  beds,  but  I  am  a  little  skeptical  as  to 
the  horizon. 


1 64  THE  DESEADO  FORMATION  OF  PATAGONIA 

Pyrotherium  Ameghino 

Pyrotherium  Amegh.,  1889,  Adas  Acad.  Nac.  Cienc.  Cordoba,  t.  VI,  p.  617. 
Pyrotherium  Lydekker,  1894,  Anal.  Mus.  La  Plata,  Palaeontologia  Argentina 

pt.  3,  p.  4. 

Pyrotherium  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  609. 
Pyrotherium  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  441. 
Pyrotherium  Amegh.,  1902,  Anal.  Mus.  Nac.  Buenos  Aires,  ser.  3,  t.  I,  p.  19-43. 
Pyrotherium  Amegh.,  1902,  Anal.  Mus.  Nac.  Buenos  Aires,  ser.  3,  t.  i,  p.  223-4. 
Pyrotherium  Gaudry,  1909,  Anal.  Palaeontologie,  t.  4,  p.  1-28. 
Parapyrotherium  Amegh.,  1902,  Anal.  Mus.  Nac.  Buenos  Aires,  ser.  3,  t.  i,  p. 

29. 

The  type  species  of  the  genus  is  P.  romeri,  which  is 
however  a  rare  species,  most  of  the  material  and  the  best 
known  belonging  to  P.  sorondoi.  The  Amherst  Collection 
contains  a  skull,  complete  except  that  the  top  of  the  brain 
case  is  crushed  in  and  the  parietals  lost;  a  second  skull 
with  the  full  upper  dentition  but  lacking  the  cranium; 
four  lower  jaws;  two  isolated  tushes;  the  atlas,  axis,  and 
crevicals  3  and  4;  the  humerus;  the  proximal  end  of  the 
femur;  and  part  of  the  front  foot;  all  from  the  Chico  del 
Chubut  west  of  Puerto  Visser.  Gaudry  had  upper  and 
lower  dentition  and  the  fore  and  hind  limbs  except  the  feet. 
Ameghino  described  the  upper  and  lower  dentitions  and 
a  fore  foot,  so  that  with  our  material  we  now  have  a  dasis 
for  a  fairly  complete  discussion,  the  vertebral  column  being 
the  major  part  which  is  still  lacking. 

The  first  striking  feature  is  the  dental  formula.  As 
formerly  given,  it  is  inaccurate,  there  being  two  great 
tushes  on  either  side  of  the  upper  jaw,  instead  of  one,  as 
described.  At  first  sight,  I  thought  it  might  be  a  meristic 
variation,  but  both  of  my  skulls  show  the  same  arrange- 
ment on  both  sides,  and  these  are  the  first  two  skulls 
which  have  been  found  complete  to  the  front  end,  and 
neither  is  by  any  means  a  young  individual.  The  dental 
formula  would  then  read  '  °  32 1 . 

Upper  incisor  I  is  a  rootless,  permanently  growing  tush 
about  a  fourth  smaller  than  inc.  2,  but  of  the  same 


PYROTHERIUM  165 

character,  being  oval  in  cross  section  and  having  enamel 
on  the  front  face  only.  These  first  incisors  are  directed 
downward,  so  that  their  ends  stand  between  and  very 
slightly  in  front  of  the  second  incisors.  The  end  of  each 
is  worn  bluntly  round  in  contrast  to  the  beveled  end  of 
inc.  2.  The  second  incisor  is  larger,  rootless,  and  perma- 
nently growing,  with  a  hollow  base,  enamel  on  the  front 
face  only,  and  oval  in  cross  section.  Both  these  teeth 
have  a  layer  of  cement  on  them,  extending  some  distance 
beyond  the  alveolus.  The  tips  are  worn  in  a  long  bevel 
on  the  posterior  side,  very  much  as  is  the  case  on  the 
incisors  of  rodents. 

The  third  upper  incisor,  the  canine,  and  premolar  I 
are  lacking,  a  long  diastema  occupying  their  place,  out 
of  which  they  have  been  crowded  by  the  development 
of  the  enormous  root  of  inc.  2,  which  extends  150  mm. 
and  more  back  into  the  jaw.  P.  romeri  is  distinguished 
from  the  others  by  pm.  I  being  present. 

The  teeth  of  the  upper  premolar-molar  series  have  their 
crowns  expanded,  and  the  two  series  of  either  side  have 
moved  toward  each  other;  until  in  front  they  are  in  con- 
tact while  in  the  rear  they  are  only  50  mm.  apart,  narrowing 
the  palate  in  a  unique  manner,  and  giving  the  impression 
that  the  palate  is  mostly  a  grinding  surface.  The  pre- 
molars  are  completely  molariform  and  the  whole  series 
is  at  an  advanced  stage  of  specialization. 

Premolar  2  is  three-rooted,  with  a  triangular  crown  on 
which  are  three  mamma-like  tubercles,  the  larger  one  in 
front,  and  two  behind.  As  the  crown  is  worn,  these  unite 
into  a  flat,  grinding  surface,  surrounding  a  central  pit 
which  opens  behind.  Premolars  3  and  4  and  all  the  molars 
are  large,  four- rooted,  quadrilateral  teeth,  each  with  two 
transverse  crests  running  clear  across  the  crown,  and  with 
a  small  cingulum  across  the  anterior  margin.  Before  they 
are  worn,  the  top  of  each  crest  is  tuberculated,  and  the 
cingulum  is  crenulated.  In  wearing,  the  anterior  face 


1 66  THE  DESEADO  FORMATION  OF  PATAGONIA 

of  each  crest  is  ground  down;  so  that  instead  of  the  crown 
wearing  to  a  level  surface,  it  retains  throughout  life  two 
oblique  grinding  surfaces. 

The  lower  dentition  is  more  reduced  than  the  upper. 
When  in  position,  the  tips  of  the  two  lower  tushes  diverge, 
so  as  to  come  in  contact  with  the  tips  of  the  second  upper 
tushes,  from  which  I  conclude  that  the  lower  tush  is  the 
second,  rather  than  the  first  incisor,  the  latter  having  been 
lost  when  the  second  became  enlarged  as  was  the  case  in 
elephants.  This  lower  tush  has  the  same  oval  cross  sec- 
tion, enamel  on  the  front  face  only,  and  beveled  tip  as  the 
corresponding  upper  incisor;  but,  in  the  same  individual, 
is  somewhat  longer  and  slenderer.  When  isolated,  how- 
ever, it  is  difficult  to  tell  whether  one  is  handling  a  small 
upper  tush  or  a  larger  lower  one. 

The  remaining  incisors,  the  canine,  the  first  and  the 
second  pre molars  are  wanting,  and  their  place  is  taken  by 
a  small  diastema.  The  lower  premolars  and  the  molars 
are  similar  to  those  of  the  upper  jaw,  except  the  cingulum 
is  on  the  posterior  margin,  and  the  wear  is  on  the  posterior 
face  of  each  transverse  crest. 

The  skull  is  very  long  and  narrow,  with  wide  and  deep 
zygomatic  arches.  The  nasal  opening  is  moved  back 
from  the  front  of  the  snout  to  just  opposite  the  orbit, 
leaving  a  long,  narrow,  but  heavy  snout,  made  up  mostly 
of  the  premaxillae,  on  the  anterior  end  of  which  is  an  ovul 
boss,  which  must  have  seiVed  as  an  attachment  for  muscles. 
With  the  tushes  developed  so  as  to  bite  against  each  other, 
as  in  a  gnawing  animal,  I  can  not  see  any  possibility  for 
the  development  of  a  pendant  proboscis,  but  think  that  the 
snout  must  have  been  developed  more  like  that  of  a  pig, 
but  probably  to  a  greater  degree.  The  premaxillae  are 
long  and  heavy,  and  prolonged  backward  to  contain  the 
roots  of  the  great  tushes;  but  these  bones  are  not  developed 
on  the  palatal  side  of  the  snout  at  all.  The  maxillae 
are  also  massive,  carrying  the  premolars  and  molars, 


PYROTHERIUM  167 

and  extending  forward  to  the  bases  of  the  tushes.  They 
have  developed  downward  so  as  to  carry  the  plane  of 
the  palate  far  below  the  plane  of  the  basicranium,  and 
causing  the  upward  bend  in  the  basicranial  axis,  which 
is  so  characteristic  of  elephants.  This  bend  leaves  the 
occipital  condyles  a  full  foot  above  the  plane  of  the  teeth. 
The  maxilla  extends  upward  so  as  to  bound  the  major 
part  of  anterior  margin  of  the  nasal  opening,  and  of  the 
orbit,  which  latter  opening  is  small  and  directed  forward. 
The  zygomatic  process  is  large  and  makes  a  considerable 
portion  of  the  arch.  The  jugal  is  a  broad  flat  bone  making 
up  most  of  the  zygomatic  arch  and  extending  back  so  as 
to  take  a  small  part  in  making  the  glenoid  fossa,  as  in 
elephants. 

The  top  of  the  brain  case  was  crushed  in  before  the 
burial  of  the  animal,  the  anterior  part  being  present, 
and  about  40  mm.  below  its  normal  position,  but  the  parie- 
tal region  having  been  loose,  exposed  the  brain  cavity,  the 
ear  chamber  and  some  of  the  cellular  vacuities.  The 
nasal  bones  are  long  and  light  in  build,  and  are  pushed  back 
so  that  they  lie  between  the  postorbital  processes  of  the 
frontals.  The  frontals  were  united  medianly,  and  pro- 
longed on  either  side  of  the  nasals  to  make  the  postorbital 
processes.  The  back  margin  of  the  frontals  is  broken 
away.  The  parietals  are  lost,  but  it  is  apparent  that  there 
was  a  short  sargittal  crest.  From  the  middle,  high  lamb- 
doidal  crests  extend  to  either  side,  and  become  continuous 
with  the  upper  margins  of  the  zygomatic  arches.  The 
posterior  face  of  the  skull  slopes  back  from  the  lambdoidal 
crests  for  a  considerable  distance,  down  to  the  moderate- 
sized  foramen  magnum. 

The  squamosum  is  a  large  bone,  with  the  lambdoidal 
crest  and  the  extension  of  the  zygomatic  arch  on  its  upper 
surface.  It  carries  the  major  part  of  the  glenoid  fossa. 
Behind  the  auditory  meatus  is  a  large  post-tympanic 
portion  which  extends  down  and  unites  with  the  pretym- 


1 68  THE  DESEADO  FORMATION  OF  PATAGONIA 

panic  portion,  completely  inclosing  the  opening  of  the 
ear  and  crowding  the  tympanic  from  being  exposed  on 
the  side  of  the  skull.  There  is  a  very  short  paroccipital 
process,  and  this  posterior  portion  of  the  squamosum  is 
the  part  which  resembles  that  of  elephants,  hyracoids 
and,  to  some  extent,  Toxodontia.  There  is,  however,  no 
cavity  in  the  squamosum  as  in  toxodonts  generally.  The 
tympanic  bulla  is  small,  but  little  swollen,  and  hollow. 
It  is  quite  exactly  like  that  of  probocideans.  The  basi- 
occipital  is  fused  to  the  exoccipitals.  The  occipital  con- 
dyles  are  very  high  above  the  plane  of  the  teeth,  are  set 
wide  apart,  and  are  cylindrical  bosses  which  would  not 
allow  a  free  movement  of  the  head  laterally,  but  only  in 
the  up  and  down  direction.  This  last  is  again  a  feature  of 
the  elephants.  The  pterygoid  bone  is  greatly  enlarged 
to  compensate  for  the  bend  in  the  basicranial  axis,  and  the 
pterygoids,  together  with  the  alisphenoids,  make  broad 
plates  bounding  either  side  of  the  posterior  nasal  chamber, 
exactly  as  in  Palaeomastodon.  The  palatal  bones  are  slender 
in  front,  and  broaden  toward  the  rear,  again,  as  in  elephants. 

On  the  interior  of  the  brain  case  is  the  cavity  for  the 
brain  which  indicates  that  this  organ  was  of  diminutive 
size,  measuring  about  150  mm.  in  length  by  50  mm.  in 
width  at  the  widest  part.  It  indicates  a  brain  with  very 
small  cerebral  hemispheres,  which,  however,  had  a  swollen 
posterior  margin,  a  larger  cerebellum,  and  a  wide  medulla 
oblongata.  The  impression  which  I  obtained  of  this  brain 
is  strikingly  like  that  given  for  Palaeomastodon.  On  either 
side  of  the  brain  cavity  are  a  couple  of  vacuities,  apparently 
for  lightening  the  weight  of  the  skull.  At  the  inner  end 
of  the  auditory  meatus  is  a  large  ear  chamber,  divided 
into  a  smaller  anterior  or  cochlear  portion,  and  into  a 
larger  posterior  ear  chamber  proper. 

In  figure  109,  I  have  placed  a  diagram  of  the  base  of 
the  skull  of  Pyrotherium,  along  beside  that  of  Palaeomas- 
todon, for  comparison  of  the  basicranial  foramena.  The 


PYROTHERIUM 


169 


A 


1 70  THE  DESEADO  FORMATION  OF  PATAGONIA 

skull  of  Palaeomastodon  is  somewhat  more  elongated, 
especially  in  the  posterior  part.  In  both,  there  are  two 
antorbital  foramena;  the  postpalatal  foramena  of  Pyro- 
therium  are  a  trifle  further  back,  but  this  palatal  region  in 
both  is  of  the  same  type  which  is  peculiar  to  elephants 
and  Pyrotherium.  In  Pyrotherium  the  condylar  foramen 
is  separate,  while  in  elephants  it  is  fused  in  with  the  fora- 
men lacerum  posterior.  This  latter  foramen  in  both  cases 
is  situated  just  back  of  the  tympanic,  and  in  Pyrotherium 
is  of  considerably  larger  size  than  in  Palaeomastodon. 
The  foramen  lacerum  medium  is  in  front  of  the  tympanic 
and  in  Pyrotherium  appears  considerably  larger,  mostly 
because  it  is  under  the  margin  of  the  tympanic  in  Palaeo- 
mastodon. The  foramen  for  the  internal  common  carotid 
in  Palaeomastodon  pierces  the  tympanic  bone  just  to  the 
inside  of  the  middle  line,  while  in  Pyrotherium  it  is  on  the 
outer  margin  of  the  tympanic.  The  Eustachian  canal  is 
on  the  external  border  of  the  tympanic  in  both  cases,  but  in 
Pyrotherium  it  is  further  back.  The  foramen  ovale  of 
Palaeomastodon  is  in  the  posterior  part  of  the  alisphenoid 
bone,  but  with  the  shorter  alisphenoid  of  Pyrotherium^ 
this  foramen  is  pushed  back  to  the  posterior  margin  of 
the  bone.  In  both  cases,  the  alisphenoidal  canal  starts 
under  the  base  of  the  fused  alisphenoid  and  pterygiod, 
and  opens  into  the  orbit.  The  stylornastoid  foramen  of 
Pyrotherium  is  situated  further  out  than  in  the  case  of 
Palaeomastodon.  The  fusion  of  the  postympanic  portion 
of  the  squamosum  is,  in  Palaeomastodon,  much  further 
advanced  than  in  Pyrotherium,  so  that  the  passage  to  the 
ear  is  not  apparent  in  the  basal  view  of  the  former,  but 
makes  a  considerable  notch  on  the  under  side  of  the  skull 
of  Pyrotherium. 

The  mandibles  are  excessively  thick  and  heavy,  being 
united  at  the  symphysis,  which  extends  back  to  the  front  of 
the  second  molar.  The  ascending  rami  are  prolonged  back- 
ward, but  do  not  rise  above  the  level  of  the  articulation. 


PYROTHERIUM  171 

The  atlas  is  a  massive  vertebra  with  the  anterior  cotyles 
deeply  excavated,  especially  on  the  upper  side,  so  that,  as 
Gaudry  suggested,  the  head  must  have  been  carried  low. 
The  flat  posterior  cotyles  face  obliquely  downward.  The 
neural  arch  is  light  and  without  a  spine  or  an  opening  for 
the  vertebral  artery.  The  basal  portion  of  the  bone,  how- 
ever, is  excessively  heavy  and  thick;  the  socket  for  the 
odontoid  process  not  reaching  to  the  middle  of  the  basal 
bar.  The  neural  canal  is  oval  in  section,  being  a  good  deal 
wider  than  high,  and  of  small  size.  The  transverse  proc- 
esses are  short,  heavy  projections,  adapted  to  receive  heavy 
muscles.  On  the  ventral  surface  there  projects  from  the 
posterior  margin  a  strong  hypophysis,  whiqh,  as  Gaudry 
has  pointed  out,  is  unusual,  but  which  is  a  character  of  the 
atlas  of  the  Palaeomastodon. 

The  axis  is  a  short,  heavy  bone,  with  the  anterior  cotyles 
facing  obliquely  upward,  a  small  neural  arch,  no  spine, 
and  with  a  thick  odontoid  process,  which  has  the  form 
of  a  quarter  of  a  hemisphere  set  onto  the  front  of  the 
centrum. 

Cervicals  3  and  4  are  very  short  vertebrae  with  light 
neural  arches  and  no  spines.  The  neural  canal  is  fully 
three  times  as  high  as  wide.  Thus  it  is  entirely  evident 
that  the  neck  of  Pyrotherium  was  extremely  short,  as  is 
the  case  with  elephants,  which  alone  would  not  be  sig- 
nificant, but  coincides  with  many  other  elephant  features. 
Gaudry  described  a  lumbar  vertebra  which  is  also  a  short, 
heavy  bone.  Otherwise  the  vertebral  column  of  Pyro- 
therium is  unknown. 

The  distal  end  of  the  scapula  is  described  by  Gaudry 
as  indicating  a  short,  heavy  bone,  with  the  glenoid  cavity 
compressed  so  as  to  be  about  twice  as  long  as  it  is  wide. 
The  coracoid  is  a  short,  blunt  process.  The  spine  was 
broken  off,  but  enough  remained  to  indicate  a  moderately 
high  spine,  prolonged  toward  the  humerus,  and  bent  some- 
what forward. 


172  THE  DESEADO  FORMATION  OF  PATAGONIA 

The  humerus  is  a  very  characteristic  bone,  short  and 
stout,  but  greatly  flattened  from  front  to  back.  It  has 
a  large  sessile  head,  which  is  strongly  convex,  and  projects 
internally  over  the  margin  of  the  shaft.  The  external 
tuberosity  is  large  and  rugose  but  does  not  project  above 
the  level  of  the  head.  The  deltoid  ridge  is  shifted  to  the 
external  side  of  the  bone,  and  makes  a  long,  muscular 
ridge,  while  on  the  opposite  external  margin  is  a  second 
ridge,  and  between  the  first  and  second  ridges  a  long  furrow 
or  trough  is  inclosed.  These  terminate  just  below  the 
middle  of  the  bone  in  roughened  bosses,  which  all  but  meet. 
The  epicondyles  are  large  and  give  the  excessive  width 
to  the  bone.  The  external  condyle  is  prolonged  upward 
and  ends  in  a  spur.  The  trochlea  is  of  moderate  width 
and  gently  undulated.  The  supratrochear  fossa  is  only 
slightly  depressed,  and  the  anconeal  fossa  is  likewise 
shallow.  The  bone  has  no  exact  counterpart,  but  is  simi- 
lar to  that  of  Moeritherium  and  Palaeomastodon,  but  in 
each  case  is  more  flattened  and  has  the  external  ridges  more 
developed. 

Gaudry  describes  the  radius  and  ulna.  They  are 
ridiculously  short,  and  very  massive.  The  ulna  is  stout 
with  a  massive  olecranon  which  is  directed  well  toward  the 
rear.  The  sigmoid  notch  is  shallow,  the  coronoid  process 
short,  and  the  articular  area  expanded  so  that  the  ulna 
covers  the  whole  of  the  posterior  of  the  trochlea  of  the 
humerus.  The  upper  end  of  the  radius  is  compressed 
antero-posteriorly,  but  distally  it  expands  into  a  heavy 
bone.  Its  upper  articulation  is  expanded,  so  that  it  comes 
in  contact  with  the  full  width  of  the  anterior  portion  of 
the  trochlea  of  the  humerus. 

The  carpus  and  front  foot  are  of  questionable  associa- 
tion. Ameghino  described  a  front  foot  as  P.  romeri,  and 
later  Tournouer  assigned  this  foot  to  Astrapotherium. 
However,  I  have  seen  no  reason  to  think  it  belongs  to 
Astrapotherium,  being  far  too  small,  and  so  would  for 


PYROTHERIUM 


173 


the  present  consider  it  as  belonging  to  Pyrotherium.  We 
found  a  couple  of  metapodials  evidently  belonging  to  the 
foot  as  described.  This  carpus 
is  of  the  primitive  type,  the  sca- 
phoid and  luna  being  large  and 
receiving  the  radius;  while  the 
pyramidal  is  smaller,  low  and 
broad  and  received  the  ulna.  The 
trapezium  is  larger  than  usual, 
being  elongated  and  standing  out 
from  the  trapezoid,  and  support- 

t  Fig.  no.  Left  carpus  and  metacarpus, 

ing    a    reduced    first    metacarpUS.    outlines  after  Xournouer— 1/5  natural 

The  trapezoid  is  also  large  and 

almost  square  in  outline.  The  magnum  is  smaller  and  con- 
siderably flattened.  The  unciform  is  very  large.  These  last 
three  mentioned  carpals  carry  the  three  medium  meta- 
carpals  which  are  quite  normal  and  seem  to  have  carried 
most  of  the  weight  of  the  animal.  Metacarpus  V  articulates 
on  the  outer  side  of  the  unciform.  It  is  a  massive  nodular 
bone  with  but  a  tiny  articulation  for  the  phalanx,  which 
seems  on  this  toe  to  have  been  reduced.  Metacarpals  IV, 
III,  and  II  are  short,  stout  bones,  flattened  from  front  to 
back,  and  enlarged  at  either  end.  On  each,  the  trochlea 
extends  well  onto  both  the  dorsal  and  palmar  surfaces,  thus 
giving  the  toes  a  considerable  range  of  movement,  and 
indicating  at  least  a  semidigitigrad  mode  of  walking. 

Of  the  pelvis,  the  ilium  is  known  as  a  broad,  heavy 
bone  with  the  acetabulum  facing  down.  The  hind  limb 
is  considerably  longer  than  the  front,  and  approximately 
pillar-like.  The  femur,  as  compared  with  the  humerus, 
is  quite  a  little  longer,  though,  as  femora  go,  it  is  not  a 
long  bone.  The  rounded  sessile  head  stands  high  above 
the  blunt,  thick  greater  trochanter;  the  digital  fossa  is 
barely  indicated;  the  rotular  trochlea  is  short;  the  two 
condyles  are  subequal  in  size  and  set  close  together.  The 
patella  is  short  and  nodular.  The  tibia  is  short  and  very 


1/4  THE  DESEADO  FORMATION  OF  PATAGONIA 

heavy.  The  fibula  is  free  its  entire  length  and  is  a  rather 
heavy  bone.  The  astragulus  is  a  lens-like  bone  with  the 
trochlea  but  slightly  convex,  and  the  navicular  facet 
directly  below  it,  indicating  a  rectigrade  foot. 

Ameghino  established  the  following  species,  P.  romeri, 
P.  sorondoi,  P.  giganteum,  P.  crassidens,  P.  trilophodon, 
P.  pluteum.  This  is  a  very  considerable  number  of  species 
of  such  a  large  type  to  occupy  a  limited  region.  Gaudry 
has  lumped  them  all  under  species  P.  romeri.  This,  I 
think,  is  too  drastic  and  T  would  find  at  least  two  species. 
It  is  true  that  there  is  great  individual  variation  in  such 
large  animals,  due  to  age,  food  supplies  and  individual 
vicissitudes;  but  where  there  is  a  difference  of  dental 
formula  or  a  structural  divergence  I  should  consider  these 
as  specific  in  character. 

The  type  species  is  P.  romeri  (later  spelled  romeroi) 
which  was  based  on  a  first  and  second  upper  premolar  and 
an  upper  tush,  all  of  smaller  size  than  P.  sorondoi  and  differ- 
ing from  all  the  others  described  in  having  pm.  I  present. 
Gaudry  suggests  that  this  may  be  the  milk  dentition  but 
there  is  no  evidence  as  yet  to  settle  this,  so  I  have  left 
this  species  standing.  Most  of  the  material  found  by 
Ameghino,  by  Gaudry  and  by  our  party  belongs  to  the 
type  described  as  P.  sorondoi,  which  is  somewhat  larger 
than  P.  romeri,  and  lacks  pm.  I  in  the  upper  jaw.  This 
then  is  the  usual  species  and  to  it  belongs  most  of  what  is 
known.  It  varies  some  in  size  but  the  characters  are 
very  uniform.  P.  giganteum  is  based  on  the  root  of  a  large 
tush,  90  by  70  mm.  in  cross  section,  which  Lydekker 
associated  with  P.  romeri,  and  which  Ameghino  later  took 
as  the  type  of  a  new  species.  I  can  see  in  this  only  a  large 
individual  of  P.  sorondoi.  P.  crassidens  is  based  on  a 
last  lower  molar  90  by  80  mm.  in  diameter.  It  seems  to 
me  to  be  an  upper  molar  and  no  larger  than  m.  2  in  either 
of  my  skulls.  P.  trilophodon  is  based  on  a  lower  pm.  3, 
which,  in  every  way,  resembles  the  corresponding  tooth 


PYROTHERIUM  SORONDOI  175 

in  lower  jaw  of  P.  sorondoi.  P.  pluteum  is  based  on  three 
lower  teeth  of  smaller  size  than  the  typical  P.  sorondoi, 
but  the  difference  is  small  and  there  are  no  structural 
features  accompanying  it;  so  I  consider  it  simply  a  smaller 
individual  of  P.  sorondoi.  In  the  generic  discussion, 
Parapyr  other  ium  planum  was  also  assigned  to  P.  sorondoi. 

Pyrotherium  romeri  Ameghino 

P.  romeri  Amegh.,  1889,  Act.  Acad.  Nac.  Cicnc.  Cordoba,  t.  VI,  p.  618. 

P.  romeri  Lydekker,  in  part,  1894,  Anal.  Mus.  La  Plata,  Palaeontologia  Argen., 

t.  Ill,  supplement,  p.  4. 

P.  romeroi  Amegh.,  1894,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  612. 
P.  romeroi  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  442. 
P.  romeroi  Amegh.,  1902,  Anal.  Mus.  Nac.  Buenos  Aires,  ser.  3,  t.  i,  p.  32. 
P.  romeri  Gaudry,  in  part,  1909,  Anal.  Paleontologie,  t.  4,  p.  21. 

This  species  is  characterized  by  the  presence  of  pm. 
I  which  is  absent  in  other  species.  The  tooth  is  of  fair 
size,  two-rooted,  narrow  in  front  and  has  a  narrow  rim  of 
enamel  around  it;  and  measures  22  mm.  long  by  14  mm. 
wide.  The  second  premolar  is  30  mm.  long  by  33  mm. 
wide.  A  lower  tush  is  also  associated  with  these  two  teeth 
and  is  of  smaller  size  than  in  the  following  species,  being 
at  the  alveolus  border  40  mm.  by  29  mm.  in  cross  section. 

Pyrotherium  sorondoi  Ameghino 

P.  sorondoi  Amegh.,  1894,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  613. 
P.  sorondoi  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  443. 
P.  sorondoi  Amegh.,  1902,  Anal.  Mus.  Nac.  Buenos  Aires,  ser.  3,  t.  I,  p.  30. 
P.  sorondoi  Amegh.,  1906,  Anal.  Mus.  Nac.  Buenos  Aires,  ser.  3,  t.  8,  p.  331. 
P.  romeri  Lydekker,  in  part,  1894,  Anal.  Mus.  La  Plata,  Paleontologia  Argen- 
tina, t.  Ill,  supplement,  p.  4. 

P.  romeri  Gaudry,  in  part,  1909,  Anal.  Paleontologie,  t.  4,  p.  21. 
P.  giganteum  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  447. 
P.  crassidens  Amegh.,  1902,  Anal.  Mus.  Nac.  Buenos  Aires,  ser.  3,  t.  i,  p.  34. 
P.  planum  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  446. 
Parapyrotherium  planum  Amegh.,  1902,  Anal.  Mus.  Nac.  B.  A.,  ser.  3, 1. 1,  p.  29. 
P.  trilophodon  Amegh.,  1902,  Anal.  Mus.  Nac.  B.  A.,  ser.  3,  t.  i,  p.  33. 
P.  pluteum  Amegh.,  1901,  Bol.  Acad.  Nac.  Cienc.  Cordoba,  t.  16,  p.  386. 
P.  pluteum  Amegh.,  1902,  Anal.  Mus.  Nac.  Buenos  Aires,  ser.  3, 1. 1,  p.  29. 

The  species  varies  in  size  and  in  the  proportionate 
development  of  the  tushes  as  would  be  expected  in  a  large 


176  THE  DESEADO  FORMATION  OF  PATAGONIA 


Fig.  in.  Top  of  the  skull — 1/5  natural  size;  Mate  to  in  i  on  the 
left  side  is  represented  by  an  alveolus  but  the  tooth  had  fallen  out 
before  the  death  of  the  animal;  a.c.,  ear  chamber;  B,  brain  case;  V, 
vacuities  in  the  bone. 


PYROTHERIUM  SORONDOI 


177 


1 78  THE  DESEADO  FORMATION  OF  PATAGONIA 

and  slow-growing  animal.  Most  all  of  the  material  found 
by  any  of  the  collectors  falls  clearly  into  this  species. 
Our  specimens  all  came  from  the  Chico  del  Chubut,  west 
of  Puerto  Visser,  which  point  is  about  250  miles  north  of 
the  locality  where  Gaudry's  material  was  found. 

The  general  features  of  the  skull  have  been  given  under 
the  generic  description.  The  difference  between  this 
and  the  preceding  species  lies  in  the  absence  of  pm.  i, 
and  the  somewhat  larger  size.  Both  of  our  major  speci- 
mens are  mutilated  in  places;  and  as  the  better  skull  was 
found  with  only  the  zygoma  tic  arch  exposed,  we  conclude 
that  the  parts  missing  were  lost  before  burial.  On  the 
lower  jaw  the  edges  of  some  of  the  teeth  were  cracked  off, 
and  both  the  ascending  rami  are  lacking,  both  things  having 
happened  before  burial,  this  specimen  being  found  well 
in  the  bank  and  never  exposed  to  weathering.  It  appears 
as  if  the  carcasses  of  the  animals  lay  some  time  before 
being  buried  by  the  sediments.  The  scattered  condition 
of  all  the  finds  indicates  the  same  thing.  The  head  of 
our  femur  is  still  marked  by  the  teeth  which  cleaned  the 
meat  from  the  bone.  The  frequency  of  isolated  tushes 
indicates  that  many  jaws  originally  containing  them  have 
been  either  chewed  to  pieces  or  weathered  away  before 
burial.  I  do  not  think  all  the  tushes  found  originally 
belonged  to  the  lower  jaw  (Gaudry  reports  18  tushes,  all 
lower);  for  the  upper  and  lower  tushes  when  isolated  are 
so  much  alike  that  it  is  difficult  to  distinguish  them. 

The  size  of  the  skull  is  indicated  by  the  following  measure- 

ments:  SPECIMEN  No.  3207 

Length  from  inc.  I  to  occipital  condyles  720  mm. 

Length  from  front  of  premax.  to  nasal  opening  225  mm. 

Length  of  boss  on  premaxilla  77  mm. 

Length  of  nasal  opening  at  top  80  mm. 

Width  of  nasal  opening  at  top  88  mm. 

Length  from  premax.  to  lambcloidal  crest  540  mm. 

Width  across  zygomatic  arches  35°  mm- 

Width  across  frontal  bones  90  mm. 

Transverse  diameter  of  the  snout  115  mm- 


PYROTHERIUM  SORONDOI 


179 


Fig.  113.  Base  of  the  skull — i/S  natural  size;  i.i,  incisor  the  right 
side  grown  over  toward  the  center  as  its  mate  is  wanting;  i.2,  in- 
cisior  2;  Pal.,  palatinum;  Ft.,  pterygoid. 


l8o  THE  DESEADO  FORMATION  OF  PATAGONIA 

The  lower  jaws  were  associated  with  the  above  skull, 
and  are  complete  to  behind  the  third  molars  on  both  sides. 
They  are  very  short  and  heavy,  especially  in  the  anterior 
portion,  the  symphysis  extending  back  to  opposite  the 
middle  of  the  second  molar.  The  height  under  molar  3 
is  150  mm.  See  frontispiece. 

From  the  upper  dentition,  I  give  the  measurements 
of  my  two  chief  specimens,  together  with  those  given  by 
Ameghino  for  his  type  of  P.  sorondoi,  and  the  figures 
given  by  Gaudry;  from  which  may  be  seen  the  amount  of 
variation  which  individuals  may  show. 

UPPER  DENTITION  SPECIMEN   SPECIMEN    AMBGHINO'S  GAUDRY'S 

No.  3207     No.  3250          TYPE        SPECIMEN 

Total  length,  inc.  I  to  m.  3  530  mm. 

Inc.  I,  length  above  alveolus  133  mm. 

Inc.  i,  antero-postcrior  diam.  49  mm. 

Inc.  I,  transverse  diam.  37  mm.  42  mm. 

Inc.  2,  length  above  alveolus  174  mm. 

Inc.  2,  antero-posterior  diam.  59  mm.  77  mm.  65  mm. 

Inc.  2,  transverse  diam.  40  mm.  52  mm.  41    mm. 

Premolar  2,  length  45  mm.  52  mm.  48  mm.       40  mm. 

Premolar  2,  width  36  mm.  40  mm.  30  mm.       29  mm. 

Premolar  3,  length  46  mm.  49  mm.  48  mm.       40  mm. 

Premolar  3,  width  57  mm.  57  mm.  46  mm.       48  mm. 

Premolar  4,  length  47   mm.  51  mm.  46  mm.       43  mm. 

Premolar  4,  width  63  mm.  64  mm.  58  mm.       57  mm. 

Molar  I,  length  55  mm.  55  mm.  57  mm.       55  mm. 

Molar  I,  width  68  mm.  69  mm.  61   mm.       61    mm. 

Molar  2,  length  68  mm.  77  mm.  70  mm.       57  mm. 

Molar  2,  width  85  mm.  93  mm.  75  mm.       68  mm. 

Molar  3,  length  75  mm.  68  mm.  83  mm.       64  mm. 

Molar  3,  width  86  mm.  87  mm.  82  mm.       88  mm. 

For  the  lower  dentition,  I  give  the  figures  which  Ame- 
ghino records  for  his  P.  sorondoi,  those  given  by  Gaudry 
for  his  P.  romeri,  and  the  measurements  of  specimen 
No.  3207.  The  tushes  in  the  lower  jaw  I  would  designate 
as  incisors  2 ;  because  when  the  jaws  are  closed  these  diverge 
and  their  tips  bite  against  the  tips  of  the  upper  incisors  2. 
The  first  incisor  seems  to  have  been  gradually  lost  and 


PYROTHERIUM  SORONDOI 


181 


no  space  left  for  it  in  the  front  of  the  mandible,  just  as  it 
was  reduced  and  lost  in  the  development  from  Moeritherium 
to  Polymastodon  or  equivalent  types. 


Tm.9 


Hit 


Fig.  114.  Lower  dentition — 1/5  natural  size;  edges  of  teeth  broken  off  in  my  specimen  are 

indicated  in  outline. 


LOWER  DENTITION 

Incisor  2  to  molar  3,  length 
Premolar  2  to  molar  3,  length 
Inc.  2,  length  above  alveolus 
Inc.  2,  antero-posterior  diam. 
Inc.  2,  transverse  diam. 
Premolar  3,  length 
Premolar  3,  width 
Premolar  4,  length 
Premolar  4,  width 
Molar  i,  length 
Molar  i,  width 
Molar  2,  length 
Molar  2,  width 
Molar  3,  length 
Molar  3,  width 


Four  cervical  vertebrae  were  preserved  with  the  skull 
number  3207,  of  which  only  about  a  third  of  the  atlas  is 
represented,  but  fortunately  we  found  a  complete  atlas 
isolated  and  of  the  same  size.  The  measurements  for 
the  atlas  are  taken  from  this  separate  specimen.  While 
my  skull,  especially  the  teeth,  seems  to  have  been  larger 
than  the  skull  Gaudry  described,  the  cervicals  are  a  little 
smaller.  I  give  the  measurements  of  the  cervicals  which 
we  found,  comparing  them  with  the  figures  given  by 
Gaudry. 


SPECIMEN 

AMEGHINO'S 

GAUDRY'S 

No.  3207 

TYPE 

SPECIMEN 

510  mm. 

540  mm.* 

415  mm.* 

325  mm. 

280  mm. 

272  mm. 

133  mm. 

188  mm.* 

168  mm.* 

55  mm. 

60  mm. 

66  mm. 

40  mm. 

36  mm. 

44  mm. 

46  mm. 

50  mm. 

54  mm. 

36  mm. 

31  mm. 

35  mm. 

55  mm. 

45  mm. 

50  mm. 

46  mm. 

45  mm. 

47  mm. 

65  mm. 

—-50  mm. 

51  mm. 

59  mm. 

52  mm. 

54  mm. 

73  mm. 

56  mm. 

66  mm. 

73  mm, 

63  mm. 

66  mm. 

69  mm. 

67  mm. 

71  mm. 

74  mm. 

66  mm. 

69  mm. 

Figures  taken  from  illustrations. 


1 82 


THE  DESEADO  FORMATION  OF  PATAGONIA 


Atlas,  antero-posterior  length  (without  hypophysis) 
Atlas,  greatest  width 
Atlas,  height 


Axis,  antero-posterior  length 
Axis,  greatest  width 
Axis,  width  of  odontoid  process 
Axis,  length  of  odontoid  process 

Cervical  3,  length  of  centrum  antero-posterior 
Cervical  3,  width  of  centrum 
Cervical  3,  height  of  centrum 
Cervical  3,  width  of  neural  canal 
Cervical  3,  height  of  neural  canal 

Cervical  4,  length  of  centrum  antero-posterior 
Cervical  4,  width  of  centrum 
Cervical  4,  height  of  centrum 


SPECIMEN 

GAUDRY'S 

3344 

SPECIMENS 

120  mm. 

140  mm. 

304  mm. 

365  mm. 

129  mm. 

140  mm. 

SPECIMEN 

3207 

116  mm. 

124  mm. 

223  mm. 

248  mm. 

96  mm. 

88  mm. 

48  mm. 

44  mm. 

47  mm.  45  mm 
125  mm.  145  mm 
105  mm.  100  mm 

75  mm. 

22  mm. 

45  mm. 
132  mm. 
105  mm. 


The  humerus  is  flattened  from  front  to  back  in  a  striking 
manner,  so  that,  seen  from  the  side,  it  looks  most  slender; 
while  in  reality  it  is  a  very  broad  bone,  nearly  straight, 
and  with  marked  rugosities  for  the  attachment  of  the 
muscles.  We  found  but  one  specimen  of  the  humerus,  an 
isolated  bone  a  little  smaller  than  that  described  by  Gaudry. 

SPECIMEN  GAUDRY'S 
No.  3218   SPECIMEN 

Humerus,  total  length  470  mm. 

Humerus,  width  at  proximal  end  232  mm. 

Humerus,  width  at  middle  of  shaft  165  mm. 

Humerus,  antero-posterior  diam.  of  shaft  61   mm. 

Humerus,  width  across  epicondylcs  230  mm.     240  mm 


500  mm. 
232  mm. 
170  mm. 


We  found  neither  the  radius  nor  the  ulna,  but  Gaudry 
figures  both,  giving  the  following  measurements. 

Radius,  length  245  mm. 

Radius,  proximal  diam.  127  mm. 

Ulna,  length  (calculated)  280  mm. 

Ulna,  width  of  olecranon  140  mm. 


PYROTHERIUM  SORONDOI 


At. 


Fig.  115.  At.,  atlas;  Ax. .axis;  €.3,  third  cervical;  C.  4, 
fourth  cervical — i/S  natural  size;  apophysis  of  atlas  is 
restored  after  Gaudry  and  the  neural  arch  of  cervical  4 
is  restored  from  the  opposite  side. 


Fig.  116.  Axis — i/5  natural  size,  front 
view. 


Fig.  117.  Anterior  face  of  the  humerus — i/S  nat- 
ural size. 


1 84  THE  DESEADO  FORMATION  OF  PATAGONIA 

For  the  hind  limb  I  give  some  of  the  figures  which  Gaudry 
gives  accompanying  his  illustrations  of  the  hind  limb. 

Femur,  length  630  mm. 

Femur,  greatest  proximal  diameter  240  mm. 

Femur,  distal  diameter  170  mm. 

Tibia,  length  370  mm. 

Tibia,  greatest  proximal  diameter  164  mm. 

Tibia,  greatest  distal  diameter  114  mm. 

Astragulus,  antero- posterior  diam.  123  mm. 

Astragulus,  transverse  diam.  114  mm. 

Astragulus,  height  65  mm. 


CHAPTER  XIII 

RODENTIA 

WHILE  all  of  small  size,  numerically  the  rodents  make 
about  a  third  of  our  collection,  the  number  of  genera 
and  species  being,  however,  relatively  small.  All  are 
hystricomorphs  with  the  pattern  on  the  crowns  of  the 
teeth  relatively  simple.  While  the  incisors  are  typically 
rodent-like,  permanently  growing  teeth,  the  molars  are 
all  rooted,  some  being  entirely  brachydont,  others  begin- 
ning to  show  hypsodont  features. 

So  far  as  yet  known,  the  rodents  make  their  first  appear- 
ance in  South  America,  in  this  Deseado  formation.  Were 
they,  as  Ameghino  thought,  developed  there  from  such  a 
form  as  Propolymastodon  or  Promysops  of  the  Casamayor 
formation?  Or  did  they  migrate  into  Patagonia  from 
some  other  section?  For  the  former  proposition  to  be 
convincing  to  me,  it  would  require  more  complete  material 
of  the  forms  suggested  than  now  exists.*  Other  groups 
of  hystricomorphs  occur  in  the  Theridomyidae  of  the 
European  Oligocene,  and  from  the  Oligocene  of  the  Fayum.f 
Either  the  old  world  forms  are  descended  from  the  South 
American  forms,  or  vice-versa.  The  two  African  lower 
jaws  are  very  much  like  those  of  Cephalomys,  and  my 
feeling  is  that  the  Patagonian  forms  are  derived  from  some 
immigrant  reaching  that  section  before  Deseado  times. 

The  Deseado  genera  are  not  widely  different  from  each 
other,  but  it  is  evident  that  they  are  the  representatives 
of  at  least  two  families,  and  my  expectation  is  that  other 
families  will  be  found  eventually  to  be  already  represented. 

*  I  have  a  lower  jaw  of  Propolymastodon  which,  though  not  complete  in 
front,  gives  me  no  suggestion  that  the  incisor  was  rodent-like,  and  I  am 
inclined  to  think  that  the  incisor  associated  with  the  type  of  P.  carlo-zitelli 
is  a  mistake. 

fOsborn,  Bui.  Amer.  Mus.  Nat.  Hist.,  Vol.  24,  p.  265. 


1 86  THE  DESEADO  FORMATION  OF  PATAGONIA 

Our  material  does  not  permit  the  discussion  of  the 
skeleton  or  even  of  the  skull  as  a  whole,  for  the  specimens 
occur  only  as  isolated  jaws,  palates,  or  even  as  isolated 
teeth.  In  a  few  cases,  the  upper  and  lower  dentitions 
are  associated,  but  in  no  case  was  skeleton  material  clearly 
associated  with  the  teeth.  The  remains  look  very  much 
like  such  as  are  often  found  today  in  the  western  United 
States  under  a  hawk's  nest  or  below  the  roosting  place  of 
owls.  I  think  most  of  our  specimens  passed,  before  burial, 
through  the  stomach  of  birds  or  carnivors. 

Ameghino  puts  most  of  the  forms  in  the  family  Cepha- 
lomidae,  which  he  considers  ancestral  to  Hystricomorpha 
in  general.  I  feel,  however,  that  it  is  better  to  assign 
the  Deseado  genera  to  the  families  which  have  persisted 
until  recent  times,  as  Scott  and  Ameghino,  in  another  place, 
have  done.  There  are  six  living  families,  four  of  which 
Scott  found  already  represented  in  the  Santa  Cruz.  Two 
of  these  clearly  may  be  continued  back  into  the  Deseado, 
the  Erethizontidae,  and  the  Chinchillidae,  nothing  as  yet 
having  been  found  to  represent  the  Santa  Cruz  families 
Cavidae  and  Octodontidae. 

Chinchillidae 

In  the  Deseado,  this  family  is  represented  by  the  genera 
Cephalomys,  Scotamys,  and  possibly  Litodontomys.  Cepha- 
lomys  is  very  abundant  and  seems  to  be  ancestral  to  Peri- 
mys  of  the  Santa  Cruz;  Scotamys  is  relatively  rare  but 
seems  to  be  ancestral  to  Scotaeumys;  while  Litodontomys 
is  also  rare  and  as  far  as  I  can  see  without  a  successor. 

Cephalomys  Ameghino 

Cephalomys  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  494. 

This  is  the  common  genus  of  the  Deseado,  over  three- 
fourths  of  the  specimens  of  rodents  found  belonging  to 
one  of  its  three  species.  Its  dental  characters  mark  it 


CEPHALOMYS  187 

clearly.  All  the  premolars  and  molars  are  rooted,  though 
the  crown  is  incipiently  hypsodont,  as  much  so  as  in  any 
rodent  of  this  period.  The  incisors  are  moderately  large 
with  the  anterior  face  slightly  convex,  and  the  antero- 
posterior  diameter  comparing  with  the  transverse  diameter 
as  3  does  to  2.  The  interval  between  the  incisor  and 
premolar  4  is  moderate,  indicating  a  short  snout. 

Each  lower  molar  consists  of  two  transverse  laminae 
separated  from  each  other  by  an  internal  and  an  external 
infolding,  both  of  which  approach  the  median  line  but  do 
not  meet,  a  narrow,  longitudinal  bar  separating  the  folds 
and  connecting  the  anterior  and  posterior  laminae.  On 
the  inner  side,  the  posterior  lamina  has  a  furrow  extending 
to  the  middle  of  the  tooth,  but  only  sinking  into  the  crown 
about  a  fourth  of  its  height,  so  that,  with  wear,  it  appears 
first  as  a  bay,  later  as  a  pit,  and  finally  disappears.  In 
general  it  will  be  found  only  on  molar  3,  and  may  be 
wanting  there  on  old  individuals.  On  an  unworn  tooth, 
there  occurs,  on  the  inner  side  of  the  anterior  lamina, 
a  rudimentary  pit  corresponding  to  the  one  .on  the  posterior 
lamina,  but  of  much  less  depth,  so  that  it  is  only  occasion- 
ally seen,  and  that  only  on  a  very  slightly  worn  tooth. 
The  premolar  differs  from  the  foregoing  in  having  a 
small  median  column  on  the  anterior  face  of  the  anterior 
lamina. 

In  three  cases  we  found  the  deciduous  fourth  premolar 
(see  fig.  H9A),  a  complicated  tooth,  consisting  primarily 
of  three  laminae  in  which  furrows  have  developed  until 
there  are  four  folds  or  furrows  on  the  internal  side,  sepa- 
rating five  crests;  while  on  the  external  side  there  are  three 
furrows  and  four  crests.  Ameghino's  figure  of  this  tooth 
in  C.  prosus  has  four  laminae  running  clear  across  the  tooth. 
I  think  the  difference  is  due  to  his  having  an  unworn  decid- 
uous premolar  whereas  mine  are  all  worn  considerably. 

At  first  glance,  the  upper  teeth  appear  strikingly  differ- 
ent, resembling  those  of  Perimys  to  which  genus  they  are 


1 88  THE  DESEADO  FORMATION  OF  PATAGONIA 

probably  ancestral.  Each  molar  consists  of  two  laminae, 
separated  by  a  deep  internal  fold  which  extends  almost 
to  the  external  margin.  On  little  worn  teeth  each  lamina 
shows,  on  the  external  side,  a  shallow  furrow  extending 
to  about  the  middle  of  the  tooth,  but  these  furrows  early 
become  pits  and  then  disappear  with  further  wear,  being 
preserved  on  not  over  a  fourth  of  our  specimens.  The 
fourth  upper  premolar  consists  of  two  laminae,  but  in  this 
case,  the  separating  fold  is  on  the  external  side  and  extends 
nearly  to  the  internal  margin,  so  that  this  tooth  appears 
to  be  reversed  in  its  position  in  the  jaw.  As  in  the  molars, 
there  is,  on.  the  external  side  of  either  lamina,  a  furrow, 
the  one  in  the  anterior  lamina  shallow  and  seldom  seen, 
that  in  the  posterior  lamina  deep  and  present  in  all  but 
the  most  worn  teeth. 

While  the  upper  and  lower  molars  appear  so  different 
they  may  be  readily  derived  from  such  a  tooth  as  the 
lower  molar,  as  both  have  the  two  laminae  and  separating 
furrows  in  common.  In  the  upper  molars,  however,  the 
internal  fold  is  prolonged  until  the  external  fold  is  merely 
indicated  or  -lacking.  On  upper  premolar  4,  on  the  con- 
trary, it  is  the  external  fold  which  is  prolonged.  The  fur- 
rows in  the  external  portions  of  the  laminae  of  the  upper 
molars  correspond  to  those  on  the  internal  portions  of 
the  same  laminae  of  the  lower  teeth,  reversed,  as  is  typical 
of  all  teeth. 

Ameghino  distinguished  three  species  of  Cephalomys, 
which  are  based  primarily  on  size,  the  other  characters 
which  he  gave  being  inconstant.  We  found  these  three 
and  no  others. 


C.  arcidens 
C.  plexus 
C.  prosus 


UPPER  PM.  4 
TOM.  3 

LOWER  PM.  4 

TO  M.  3 

13-14  mm. 
9.5  mm. 
8.5  mm. 

14-15  mm. 
10.5  mm. 
9.5  mm. 

CEPHALOMYS  ARCIDENS 


189 


Fig.  118.    Right  upper  premolar,  molar 
series  x  4/1. 


Cephalomys  arcidens  Ameghino 

C.  arcidens  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  494. 

This,  the  type  species,  is  by  far  the  commonest  of  the 
rodents,  in  fact  of  all  the  species  in  the  Deseado,  and  we 
found  forty-seven  specimens 
on  the  Chico  del  Chubut 
River,  west  of  Puerto  Visser. 
In  the  species  there  is  con- 
siderable variation  in  size  for 
a  rodent,  but  as  there  are  intermediate  specimens  all  the 
way  between  the  extremes,  and  as  the  variation  is  mostly 

in  the  size  of  the  fourth 
premolar,  it  does  not 
seem  proper  to  separ- 
ate the  material  into 
more  than  one  species. 
In  general,  the  form 
has  relatively  plump 


teeth,  relatively  heav- 
ier anct~  thicker  than 
in  the  other  species. 
Usually  the  fourth 
premolar  is  but  little 
larger  than  the  molars, 

Fig.  119.  Left  lower  premolar,  molar  series;  A,  decodu-    l-tnf-     iti    fliic  r-Viot-a/^foi- 
ous  premolar  4;   B,  a  little  worn  mola  i ;  C,  series  about     l    JL»    1U    l  Cl ' 

^^^^^i^^^^tS&l^^.  there    is   considerable 

variation.  The  fol- 
lowing measurements  give  the  range  of  size  on  the  upper 
jaws: 


Upper  premolar  4  to  m.  3 
Upper  premolar  4,  length 
Each  molar,  length 
Each  molar,  width 


SPECIMEN 

SPECIMEN 

AMEGHINO'S 

3109 

3099 

TYPE 

A  SMALL 

A  LARGE 

INDIVIDUAL 

INDIVIDUAL 

12.5  mm. 

13.5  mm. 

13.5  mm. 

3-5  mm- 

4.5  mm. 

3       mm. 

3       mm. 

2.75mm. 

3       mm. 

190 


THE  DESEADO  FORMATION  OF  PATAGONIA 


The  lower  jaw  is  low,  heavy  and  rather  short,  the 
posterior  part  of  the  ramus  being  very  thin,  while  the 
portion  carrying  the  teeth  is  thick  and  heavy.  A  strong 
ridge  extends  along  the  inner  side  from  just  behind  molar  3 
to  the  base  of  the  symphysis.  As  in  the  upper  dentition, 
there  are  smaller  and  larger  forms. 

SPECIMEN        SPECIMEN  AMEGHINO'S 

3089  3058  TYPE 

A  SMALL  A  LARGE 

INDIVIDUAL      INDIVIDUAL 
Lower  premolar  4  to  m.  3 
Lower  incisor  I  to  pm.  4 
Height  of  mandible  under  pm.  4 
Length  of  deciduous  pm.  4 


14       mm. 

15  mm. 

14.5  mm 

7       mm. 

9  mm. 

7.8  mm 

7       mm. 

8  mm. 

7       mm 

5-5  mm- 

Cephalomys  plexus  Ameghino 

C.  plexus  Amegh.,  1897,  Bol  Inst.  Geog.  Argen.,  t.  18,  p.  494. 

In  general,  this  species  is  similar  to  the  foregoing,  but 

is  smaller  in  size  and  slenderer 
in  proportions.  Both  the  upper 
and  lower  fourth  premolar  tend 
to  be  considerably  larger  than 
the  molars.  The  species  was 
not  nearly  as  abundant  as  C. 
Fig.  120. "Right  paiaiate  showing  Pre-  arcidens,  occurring  but  sixteen 

molar,    molar   series;   external  furrows       •  i«        .• 

appear  as  pits  on  molars  2  and  3,  x  4/1.     timCS     in     OUr     Collection. 


Fig.  121.  Left  mandible,  external  side,  x  4/1. 


CEPHALOMYS  PLEXUS 


191 


MEASUREMENTS 

Upper  dentition,  pm.  4  to  m.  3 
Upper  dentition,  pm.  4,  length 
Upper  dentition,  each  molar  length 
Upper  dentition,  each  molar  width 


SPECIMEN 

3091 

9.  mm. 
2.75  mm. 
2.1  mm. 
2.25  mm. 


AMEGHINO  's 

TYPE 
9.5  mm. 


The  lower  jaw  is  slender,  the  incisor  being  relatively  both 
smaller  and  slenderer  than  in  C.  arcidens;  the  back  part 
of  the  ramus  light  and  thin,  the  coronoid  process  being  a 
tiny  spur,  and  the  articular  condyle  of  small  size,  and  on  a 
level  with  the  teeth. 


MEASUREMENTS 

Lower  dentition,  pm.  4  to  m.  3 
Lower  dentition,  in.  i  to  pm.  4 
Lower  dentition,  pm.  4,  length 
Lower  dentition,  each  molar,  length 
Lower  dentition,  each  molar,  width 
Height  of  mandible  under  pm.  4 

int. 


ext. 

Fig.  122.  C.  plexus,  left  lower  premolar, 
molar  series;  A,  of  young  individual;  B, 
of  old  individual;  inf.,  internal  side;  ext., 
external  side,  X4/I. 


SPECIMEN        AMEGHINO'S 


3005 

10  mm. 
6  mm. 
3-5  mm- 
2.5  mm. 
2  mm. 
mm. 


TYPE 
10.5  mm. 
6.5  mm. 


4.8  mm. 


Fig.  123.    C.  prosus,  left  upper 
premolar ,'_molar  series,  x  4/1. 


Fig.  124.    C.  prosus,  premolar  4 
and  molar  2,  x4/i. 


Cephalomys  prosus  Ameghino 

C.  prosus  Amegh.,  1902,  Bol.  Acad.  Nac.  Cienc.  Cordoba,  t.  17,  p.  37. 

This  is  the  tiniest  species  of  the  genus,  and  least  fre- 
quently found,  probably  because  on  account  of  the  small 
size  it  was  more  frequently  destroyed  before  burial,  and 
also  because  it  is  hard  to  find  such  tiny  specimens;  so  that 


1 92  THE  DESEADO  FORMATION  OF  PATAGONIA 

the  sixteen  which  we  found  would  hardly  represent  the 
real  proportion  of  the  species  in  the  fauna. 

The  jaws  are  not  only  small,  but  also  slender  and  deli- 
cately built,  with  the  premolar  about  the  same  size  or 
slightly  larger  than  the  molars.  The  drawings  represent 
the  proportions  accurately  so  I  will  give  but  a  few  measure- 
ments. 

SPECIMEN  AMEGHINO'S 

3009  TYPE 

Upper  premolar  4  to  molar  3  8,5  mm. 

Lower  premolar  4  to  molar  3  95  mm. 

Scotamys  gen.  nov. 

A  lower  jaw,  with  premolar  4  and  molars  I  and  2,  from 
the  Deseado  beds  on  the  Chico  del  Chubut  River,  west  of 
Puerto  Visser,  indicates  a  genus  of  hystricomorph  rodents 
not  previously  reported.  The  lower  molars  suggest  those 
of  Perimys,  but  premolar  4  is  similar  to  that  of  Scotaeumys 
from  the  Santa  Cruz.  Scotamys  differs,  however,  from 
Scotaeumys,  in  that  its  molars  do  not  have  the  third  lobe 
found  in  the  Santa  Cruz  genus.  I  have,  therefore,  made 
a  new  genus  which  appears  to  be  ancestral  to  Scotaeumys. 

Scotamys  antiquus  sp.  nov. 

This,  the  type  species  of  the  above  genus,  is  based  on 
specimen  3063,  a  lower  jaw  with  the  incisor,  premolar  4 
and  the  first  two  molars.     The  incisor 
is  fairly  large  and  heavy,  the  anterior 
face  slightly  convex,  and  the  anterio- 
Fig.T2S.   Lo^er  pTei^iar  4    posterior  diameter  greater   than   the 
transverse  diameter.    Premolar  4  has  a 

deep  external  fold,  dividing  the  crown  into  an  anterior 
and  posterior  lamina,  the  former  being  then  subdivided 
by  another  external  fold,  making  the  tooth  three-lobed. 
Just  internal  to  the  median  fold  is  a  tiny  pit,  apparently 
the  last  vestige  of  an  internal  fold.  Each  molar  consists 


SCOTAMYS  193 

of  two  laminae  separated  by  a  deep  external  fold,  around 
the  inner  end  of  which  the  laminae  are  connected  by  a 
narrow  bar.  In  the  present  condition  of  wear  there  is  no 
indication  of  secondary  furrows.  The  premolar  is  smaller 
than  the  molars. 

MEASUREMENTS  SPECIMEN  3063 

Lower  dentition,  in.  I  to  pm.  4  8         mm. 

Lower  dentition,  premolar  4  length  3         mm.,  width    2.5  mm. 

Lower  dentition,  molar  I  length  2.5     mm.,  width    2.5  mm. 

Lower  dentition,  molar  2,  length  2.75  mm.,  width    3       mm. 

Height  of  mandible  under  pm.  4  5.5     mm. 


Fig.  126.  Left  mandible  external  side,  x  4/1. 

Litodontomys  gen.  nov. 

One  set  of  lower  teeth  found  by  the  Amherst  party 
shows  a  simplicity  of  pattern  found  in  no  other  genus  of 
South  America;  and  this  is,  therefore,  named  Litodontomys. 
The  teeth  are  brachydont,  the  premolar  and  the  molars 
each  being  divided  into  two  laminae  by  an  external  and 
an  internal  fold,  the  distinctive  generic  feature  being  in 
that  this  fold  is  narrowest  at  the  margin  of  the  tooth  and 
expands  internally.  In  connection  with  the  expanded 
folds,  the  ends  of  the  laminae  are  curved  toward  each  other, 
so  that  in  a  worn  specimen  they  would  meet  on  the  margins 
of  the  tooth,  and  leave  the  folds  to  appear  as  pits.  No 
indication  of  a  furrow  is  evident  on  either  lamina. 


194  THE  DESEADO  FORMATION  OF  PATAGONIA 

Litodontomys  chubutensis  sp.  nov. 

The  type  is  number  3086  of  the  Amherst  collection, 
from  the  Deseado  beds  on  the  Chico  del  Chubut  River,  west 

of  Puerto  Visser,  and  consists  of 
the  lower  premolar-molar  series. 
Premolar  4  is  elongated,  the 
Fig.  127.  Right jower/prcmoiar4-moiar   anterior  lamina  being  consider- 
ably   longer    than    it    is    wide, 

whereas  the  laminae  of  the  other  teeth  are  wider  than  they 
are  long. 

The  following  measurements  with  the  figure  give  the 
specific  details. 

Lower  dentition,  premolar  4,  to  molar  3  10.5  mm. 

Lower  dentition,  premolar  4,  length  3.5  mm. 

Lower  dentition,  molar  I,  length  2.  mm. 

Lower  dentition,  molar  2,  length  2.5  mm. 

Lower  dentition,  molar  3,  length  2.5  mm. 

Lower  dentition,  width  of  molars  2 .  mm . 

ERETHIZONTIDAE 

Asteromys  Ameghino 

Asteromys  Amegh.,  1897,  Bol.  Inst.  Geog.  Argcn.,  t.  18,  p.  495. 

The  genus  contains  small  forms,  with  brachydont  teeth. 
The  upper  molars  consist  of  two  laminae,  separated  by  an 
internal  and  an  external  fold,  and  each  lamina  having, 
on  the  internal  half,  a  deep  furrow,  which  is  but  little 
shallower  than  the  median  fold;  so  that  the  outer  side 
shows  three  furrows,  folds,  or  pits,  more  or  less  completely 
separating  four  lobes;  while  on  the  inner  side  of  the  tooth 
there  are  but  two  lobes.  On  the  lower  teeth  the  external 
median  fold  is  deep,  while  the  internal  median  fold  is 
shallower,  usually  appearing  as  a  pit.  Both  the  anterior 
and  posterior  laminae  are  subdivided  by  wide  internal 
furrows  which  extend  to  the  median  line. 

These  characters  associate  the  genus  with  Acaremys  of 
the  Santa  Cruz,  from  which  genus  it  is  not  easy  to  separate 


ASTEROMYS  195 

Asteromys;  but  as  we  know  only  the  teeth  from  the  Deseado 
beds,  it  is  probable  that,  when  the  skull  is  found,  larger 
differences  will  be  recognized.  Asteromys  appears  to  be 
the  direct  ancestor  to  Acaremys. 

The  species  are  all  tiny,  the  following  three  being  dis- 
tinguished by  Ameghino. 

LENGTH  OF  LOWER 

•  MOLAR  SERIES 

A.punctus  (Bol.  Inst.Geog.  Argen.,  1897,  t.  18,  p.  495)  12  mm. 

A.  annectens  (Bol.  Acad.  Nac.  Cienc.  Cordoba,  1902,  t.  1 7,  p.  37)         1 1   mm. 
A.  prospicuus  (Bol.  Inst.  Geog.  Argen.,  1897,  t.  18,  p.  495)  each  molar  1.6  to 
1.8  mm. 

Of  these  three  we  found  only  the  last. 


Asteromys  prospicuus  Ameghino 

A.  prospicuus  Amegh.  loc.  cit.  above. 

The  species  is  rare,  only  three  specimens  turning  up  in 
our  collections.     The  upper  molars  are  as  described  in 


Fig.  128.  Right  tipper  premolar  4—  Fig.  129.  Left  lower 

molar  3,  x  4/1.  molar  2,  x  4/1. 

the  generic  discussion,  but  premolar  4  is  simpler  than  the 
molars,  the  posterior  lamina  being  small  and  without  any 
sort  of  furrow.  In  the  upper  molars  the  anterior  lamina 
is  larger  than  the  posterior,  and  the  anterior  furrow  wider 
than  the  posterior.  The  following  measurements,  with 
the  figures,  indicate  the  character  of  the  species. 

Upper  dentition,  premolar  4  to  molar  3  8.75  mm. 

Upper  dentition,  premolar  4,  length  2.  mm. 

Upper  dentition,  each  molar,  length  2.3  mm. 

Upper  dentition,  each  molar,  width  2 .  mm. 

Lower  dentition,  molar  2,  length  2-75  nun. 

Lower  dentition,  molar  2,  width  1 . 75  mm. 


196  THE  DESEADO  FORMATION  OF  PATAGONIA 

Eosteiromys  Ameghino 

Eosteiromys  Amegh.,  1902,  Bol.  Acad.  Nac.  Cienc.,  Cordoba,  t.  17,  p.  no. 

The  genus  was  established  by  Ameghino  for  forms  similar 
to  Steiromys  of  the  Santa  Cruz,  but  antedating  that  time. 
I  confess  I  can  see  but  little  difference  between  Steiromys 
and  Eosteiromys,  but  the  latter  is  as  yet  known  only  from 
isolated  teeth  and  as  in  general  it  would  be  expected  that 
there  should  be  a  generic  difference,  we  may  let  this  genus 
stand  representing  rather  a  prophecy  than  the  facts  as 
yet  known. 

The  upper  teeth  are  brachydont,  the  crown  being  on 
the  same  general  plan  as  in  the  foregoing  genus,  i.  e.,  it 
is  divided  into  an  anterior  and  posterior  lamina  by  a  deep 
external  median  fold  and  by  a  shorter  oblique  internal  me- 
dian fold.  The  anterior  lamina  is  subdivided  by  two  ex- 
ternal furrows,  a  lesser  anterior  and  a  larger  posterior; 
while  the  posterior  lamna  is  subdivided  by  a  single  external 
furrow;  so  that  this  tooth  has  four  folds,  furrows,  or  pits 
on  the  external  side  separating  five  lobes;  while  on  the 
inner  side  there  is  but  the  one  oblique  fold  separating  two 
lobes. 

Eosteiromys  medianus  Ameghino 

?  E.  medianus  Amegh.,  1902,  Anal.  Mus.  Nac.  Buenos  Aires,  ser.  3,  t.  2,  p.  129. 

The  genus  is  based  on  a  single,  though 
entirely  characteristic,  upper  molar.  We 
found  just  one  tooth  of  the  species,  also  an 
upper  molar.  It  is  described  above,  under 
the  genus.  The  measurements  are :  Upper 
FigmoLR2i8xV/TPer  molar  2>  ^ngth  4  mm.,  width  5  mm. 


CHAPTER  XIV 

EDENTATA 

THE  scarcity  of  edentates  in  the  Deseado  beds  is  in 
striking  contrast  to  their  abundance  in  the  Santa  Cruz 
formation.  Whereas  in  this  latter  horizon  over  half  of  the 
finds  are  edentates,  in  the  Deseado  only  eight  per  cent,  of 
the  total  collection  belong  to  this  group,  and  this  is  doubt- 
less a  larger  proportion  than  these  animals  jepresented  in 
the  fauna;  for  the  hundreds  of  small  plates  in  a  carapace, 
when  scattered  greatly,  increase  the  chance  that  some  part 
of  an  individual  will  be  found,  and  most  of  the  eight  per 
cent,  of  finds  are  single  plates.  Most  of  the  plates  found 
represent  armadilloes,  our  collection  containing  but  one 
plate  of  a  glyptodont,  and  no  gravigrades.  Ameghino's 
collections  present  about  the  same  relations,  but  in  the 
repeated  trips  he  found  a  few  more  traces  of  glyptodons 
and  a  very  few  gravigrades. 

This  scarcity  of  edentates  can  not  be  taken  to  mean  that 
they  were  not  developed,  for  they  are  a  peculiarly  South 
American  group,  and  as  they  were  developing  somewhere 
into  their  great  complexity,  I  take  it  to  mean  that  the 
climatic  conditions  were  unfavorable  in  this  particular 
section. 

As  noted  above,  all  previous  finds  have  been  isolated 
plates.  We  were  fortunate  enough  to  find  one  specimen 
consisting  of  a  carapace  with  ten  rows  of  movable  plates 
in  place,  and  parts  of  four  rows  of  the  pelvic  buckler  to- 
gether with  over  fifty  isolated  plates.  A  second  specimen 
had  some  fifty  associated  plates  which  were  mostly  from 
the  pelvic  buckler. 

Dasypoda 

The  representatives  of  this  group  are  so  poorly  known 
in  the  Deseado  beds  that  Ameghino  has,  in  general,  used 


198 


THE  DKSRADO  FORMATION  OF  PATAGONIA 


the  generic  names  of  the  Santa  Cruz  for  their  description, 
and,  so  far  as  known,  they  are  little  differentiated  from 
those  genera.  There  is  as  yet  no  material  which  shows  the 
association  of  skeletal  parts  with  the  carapaces.  There- 
fore, in  this  paper,  comparisons  are  made  wholly  on  the 
carapace,  with  the  expectation  that  the  skeleton,  when 
found,  will  correspond. 

The  Deseado  species  are  but  little  less  specialized  than 
the  Santa  Cruz,  the  carapace  consisting  of  movable  over- 
lapping bands  of  plates  both  in  the  anterior  and  body 
portions,  while  over  the  pelvic  region  the  plates  are  fixed, 
do  not  overlap,  and  form  a  pelvic  buckler. 

Ameghino  has  described  a  considerable  number  of  genera 
based  on  isolated  plates,  to  which  I  refer  later.  The 
chief  genera  which  occur  in  these  beds  are  also  found  in  the 
Santa  Cruz,  and  the  distinguishing  features  are  as  follows: 


CEPHALIC  SHIELD 

MOVABLE  PLATES 

PELVIC  BUCKLER 

ORNAMENTATION 

Proeutatus 

Plates  thin,  coarsely 
pitted 

Plates  thick,  J  over- 
lapped 

8  -|~  probably     10 
rows 

"Flask"  figure 

Prozaedius 

Plates  thin,  finely 
pitted 

14    bands,    thin,     \ 
overlapped 

8  rows 

3      long       ridges, 
median  ridge  nar- 
row 

Stenotatus 

Plates  thick.coarsely 
pitted 

Plates      thick      and 
wide 

1  1  rows 

3  long  ridges,  all 
subequal 

Proeuphractus 

J  overlapped 

No  buckler 

Peltephilus 

19  or  21  Plates  2  or  4 
horns 

Wide  and   thin  2-4 
wide  pita 

Buckler 

Large  shallow  pits 

Proeutatus  Ameghino 

Eutatus  Amegh.,  in  part,  1887,  Bol.  Mus.  La  Plata,  t.  I,  p.  25. 
Proeutatus  Amegh.,  1891,  Revista  Argen.  d.  Hist.  Nat.,  t.  I,  p.  327. 
Thoracothcrium  Mercetat,  1891,  Revista  Mus.  La  Plata,  t.  2,  p.  42. 
Eutatus  Lydekker,  in  part,  1894,  Anal.  Mus.  La  Plata,  t.  3,  p.  62. 
Proeutatus  Scott,  1903-5,  Reports  Princeton  Patagonian  Exp.,  vol.  5,  p.  40. 

This   is    the    most   frequently   occurring   genus   in    the 
Deseado,  but  is  as  yet  represented  only  by  isolated  plates. 


PROEUTATUS 


199 


The  genus  is  distinguished  by  thick,  relatively  long  and 
narrow,  movable  plates,  each  overlapped  by  about  a  third 
of  its  length.  The  plates  of  the  pelvic  buckler  are  shorter 
and  thicker,  the  exposed  surface  of  each  being  ornamented 
by  a  figure  compared  by  Ameghino  to  a  flask  (see  fig.  131), 
which  figure  is  more  distinct  on  the  rear,  fading  away 
toward  the  front.  On  the  plates  of  the  pelvic  buckler 
this  figure  is  more  accentuated,  and  from  it,  on  either  side, 
radiate  two  furrows  dividing  the  surface  into  several  (4  to 
5)  areas.  The  entire  surface  of  each  plate  is  irregularly 
punctate. 

Proeutatus  lagenaformis  Ameghino 

P.  sp?  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  660. 

P.  lagenaformis  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  507. 

On  the  Chico  del  Chubut  River,  west  of  Puerto  Visser, 
we  found  nine  specimens  of  this  species,  all  fragmentary, 
though  one  consists  of  over  fifty 
more  or  less  broken  plates,  mostly 
from  the  pelvic  buckler.  This  is 
the  only  species  of  the  genus  from 
the  Deseado,  and  corresponds  to 
the  description  above.  A  movable  _P 

plate  generally  measures  about  28     Fig.  131.  A , movable Piate; Band 

II  •  i  *  i  C,  plates  from   pelvic  buckler — nat- 

mm.  long  by  10  mm.  wide,  and  has  urai T size. 

four  large  piliferous  pits  on  the  posterior  margin.     A  plate 

of  the  pelvic  buckler  varies  greatly  in  size,  but  is  always 

thick  and  has  two  to  eight  piliferous  holes  on  the  posterior 

margin.     A  typical  plate  measures  20  mm.  long  by  10  mm. 

wide. 

Prozaedius  Ameghino 

Zaedius  Amegh.,  in  part,  1889,  Act.  Acad.  Nac.  Cordoba,  t.  5,  p.  867. 
Prozaedius  Amegh.,  1891,  Revista  Argen.  Hist.  Nat.,  t.  I,  p.  327. 
Dasypus  Lydekker,  in  part,  1894,  Anal.  Mus.  La  Plata,  t.  3,  p.  55. 
Prozaedius  Scott,  1903-5,  Reports  Princeton  Patagonian  Exp.,  vol.  5,  p.  69. 

Of  this  little  genus,  which  is  so  strikingly  like  the  living 
Zaedius ,  we  found  a  carapace  with  ten  rows  of  movable 


f 


200  THE  DESEADO  FORMATION  OF  PATAGONIA 

plates  in  place,  parts  of  four  rows  of  fixed  plates  from  the 
pelvic  buckler,  and  some  caudal  vertebrae.  The  genus  is 
distinguished  by  its  thin  plates,  there  being  fourteen  bands 
of  movable  plates,  and  eight  rows  in  the  pelvic  buckler. 
The  movable  plates  are  narrow,  each  overlapped  about  a 
fourth  of  its  length,  and  have  a  faint  ornamentation,  with  no 
piliferous  pits  except  on  the  posterior  margin.  The  fixed 
plates  are  similar,  except  that  they  are  shorter,  and  have 
the  ornamentation  more  accentuated,  with  radial  grooves. 
Ameghino  has  described  three  species  as  follows: 

P.  impressus,  sculpture  little  accentuated,  post,  piliferic  pits  rudimentary. 
P.  planus,  sculpture  more  accentuated,  post,  piliferic  pits  lacking. 
P.  tenuissimus,  very  small. 

In  my  specimen,  the  two  anterior  rows  of  movable  plates 
lack  the  marginal  piliferous  pits,  on  the  next  two  rows  they 
are  rudimentary  (which  is  also  true  of  the  lateral  plates 
even  further  back) ,  while  on  the  bulk  of  the  movable  plates 
and  on  those  of  the  pelvic  buckler  there  are  two,  three  or 
four  good-sized  piliferous  pits  on  the  rear.  I  can  therefore 
recognize  but  two  species,  P.  impressus  and  P.  tenuissimus. 

Prozaedius  impressus  Ameghino 

P.  impressus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  508. 
P.  planus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  509. 

Our  specimen  was  found  on  the  Chico  del  Chubut  River, 
west  of  Puerto  Visser,  and  preserves  over  two  hundred 
plates,  and  eight  caudal  vertebrae.  The  anterior  rows  of 
plates  of  the  carapace  consist  of  thin  plates  overlapping 
about  a  fourth  their  length.  Just  behind  the  overlap,  there 
is,  on  each,  a  group  of  small  punctations,  and  the  exposed 
part  of  the  surface  is  divided  by  two  shallow  furrows, 
making  three  more  or  less  equal  ridges  which  die  out  toward 
the  rear,  leaving  the  posterior  part  of  the  plate  plain. 
These  most  anterior  plates  are  bent  to  one  side  and  have 
no  piliferous  pits  on  the  rear  margin.  The  plates  of  the 
third  and  fourth  rows  are  not  bent,  and  have  the  sculpture 
more  distinct,  the  extreme  lateral  plates  having  no  piliferous 


PROZAEDIUS  IMPRESSUS 


201 


Fig.  132.  Portion  of  carapace — natural  size;  unshaded  plates  are  from  cast;  a  and  b  plates  from  pelvic  buckler. 


202  THE  DESEADO  FORMATION  OF  PATAGONIA 

pits,  the  median  lateral  plates  with  rudimentary  piliferous 
pits,  and  the  dorsal  ones  with  well  marked  posterior  pits. 
In  each  succeding  row  toward  the  rear,  the  plates  are  more 
distinctly  ornamented  and  have  larger  posterior  marginal 
pits.  I  have  no  marginal  plates. 

The  plates  of  the  pelvic  buckler  do  not  overlap,  are 
shorter,  have  a  very  distinct  figure,  and,  in  addition  to  the 
longitudinal  furrows,  have  a  couple  of  radial  furrows  on 
either  side,  which  divide  the  plate  into  four  or  five  areas 
(see  fig.  132  a  and  b). 

The  caudal  vertebrae  are  short  and  thick,  indicating  a 
short  tail.  I  found  no  plates  which  would  indicate  a  caudal 
shield,  which  coincides  with  the  experience  among  the 
Santa  Cruz  specimens.  The  figures  are  to  scale  and  give 
most  of  the  measurements. 

There  are  ten  rows  of  movable  plates,  probably  two  to  three  rows  lacking. 

There  are  twenty  +  plates  to  a  row. 

A  typical  movable  plate  measures  17  mm.  long  by  6  mm.  wide. 

There  were  at  least  four  rows  in  the  pelvic  buckler,  probably  eight  as  in  the 

Santa  Cruz. 
A  typical  fixed  plate  measures  10  mm.  long  by  5  mm.  wide. 

Prozaedius  tenuissimus  Ameghino 

P.  tenuissimus  Amegh.,  1902,  Bol.  Acad.  Nac.  Cienc.  Cordoba,  t.  17,  p.  66. 

This  species  is  characterized  by  Ameghino  on  account 
of  its  small  size.  The  movable  plates  have  two  furrows 
which  converge  toward  the  front,  and  between  which  is  a 
median  crest.  In  the  furrows  are  two  rows  of  perforations. 
A  movable  plate  measures  9  mm.  long  by  4  mm.  wide. 

Stenotatus  Ameghino 

Euphractus  Ameghino,  in  part,  1887,  Bol.  Mus.  La  Plata,  t.  I,  p. 26  of  separate. 

Dasypus  Amegh.,  in  part,  1889,  Act.  Acad.  Nac.  Cienc.  Cordoba,  t.  5,  p.  864. 

Stenotatus  Amegh.,  1891,  Revisla  Argen.  Hist.  Nat.,  t.  I,  p.  253. 

Dasypus  Lydekker,  1894,  Anal.  Mus.  La  Plata,  t.  3,  p.  55. 

Prodasypus  Amegh.,  1894,  Bol.  Acad.  Nac.  Cienc.  Cordoba,  t.  13,  p.  172  of 

separate. 
Stenotatus  Scott,  1903-5  Princeton  Patagonian  Exped.,  vol.  5,  p.  80. 

The  genus  is  very  like  Prozaedius  but  differs  in  having 
thicker  and  wider  movable  plates,  in  having  more  rows  of 


PROEUPHRACTUS  203 

plates  in  the  pelvic  buckler  (n),  and  in  details  throughout 
the  skeleton.  We  found  no  representatives  of  the  genus, 
but  Ameghino  has  described  a  species  (no  figure),  S. 
(Prodasypus)  ornatus*  based  on  isolated  plates.  A  mov- 
able plate  measures  18  mm.  long  by  6-7  mm.  wide,  while 
a  fixed  plate  measures  9  mm.  long,  by  6-7  mm.  wide. 

Proeuphractus  Ameghino 

Proeuphractus  Amegh.,  1886,  Bol.  Acad.  Nac.  Cienc.  Cordoba,  t.  9,  p.  208. 

This  genus  is  seldom  found,  but  is  distinguished  by  Ame- 
ghino by  the  absence  of  a  pelvic  buckler,  all  the  plates  of  the 
crapace  being  movable.  From  the  Deseado  beds,  Ameghino 
describes  two  species,  P.  setiger  and  P.  laevis,  both  based  on 
isolated  plates;  the  former  distinguished  by  having  no  pilif- 
erous  perforation  in  the  furrows  surrounding  the  central 
figure,  and  with  well-developed  pits  on  the  posterior  margin; 
while  the  latter  has  small  piliferous  perforations  in  the  fur- 
rows and  only  rudimentary  ones  on  the  posterior  margin. 
These  features  do  not  seem  to  me  to  distinguish  species. 

In  addition  to  the  foregoing,  Ameghino  has  made  a 
series  of  genera  and  species,  f  Archaeutatus,  Amblytatus, 
Isutaetus,  Sadypus,  Hemiutatus,  Anutaetus,  all  based  on 
isolated  plates,  and  distinguished  by  variations  in  the 
central  figure  and  the  piliferous  pits.  I  am  unable  to  find 
a  satisfactory  basis  for  distinguishing  the  genera  or  species, 
and  feel  that,  until  more  complete  material  is  known,  it  is 
impossible  to  say  which  are  valid  genera, or  species. 

Peltephilus  Ameghino 

Peltephilus  Amegh.,  1887,  Bol.  Mus.  La  Plata,  t.  I,  p.  25  of  separate. 
Cochlops  Amegh.,  in  part,  1889,  Act.  Acad.  Nac.  Cienc.  Cordoba,  t.  5,  p.  792. 
Gephyranodon  Amegh.,  1891,  Revista  Argen.,  Hist.  Nat.,  t.  I,  p.  119. 
?  Anatiosodon  Amegh.,  1891,  Revista  Argen.  Hist.  Nat.,  t.  I,  p.  327. 
Peltephilus  Scott,  1903-5,  Princeton  Patagonian  Exped.,  vol.  5,  p.  88. 

While  rare,  this  genus  is  well  known  from  the  Santa 
Cruz,  and  is  characterized  by  the  curious  development  of 

*Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  508,  1897. 

t  Bol.  Acad.  Nac.  Cienc.  Cordoba,  t.  17,  p.  56-66,  1902,  no  figures. 


204  THE  DESEADO  FORMATION  OF  PATAGONIA 

the  head  shield,  which  consists  of  nineteen  or  twenty-one 
definitely  arranged  head  plates,  the  anterior  ones  being 
developed  into  horn-like  projections.  The  plates  of  the 
carapace  are  wide,  thin,  and  unique  in  each  having  two 
to  four  wide  shallow  pits  on  the  exposed  surface.  We  found 
the  genus  rare,  only  two  isolated  plates  turning  up.  From 
the  Deseado  material  Ameghino  has  made  three  species: 
P.  protervus,  of  very  large  size;  P.  undulatus,  of  moderate 
size,  with  the  median  figure  accentuated  and  ending  in  two 
pits  and  with  piliferous  depressions  on  the  margin;  and  P. 
depressus,  of  the  same  size  as  the  foregoing,  with  a  faint 
central  figure,  often  four  pits  on  the  exposed  surface  and 
no  piliferous  pits  on  the  margin.  We  found  but  one  species, 
one  plate  of  which  combines  characters  of  both  the  last 
two  as  described,  so  that  I  feel  that  there  should  be  but 
two  species,  P.  protervus  and  P.  undulatus. 

Peltephilus  undulatus  Ameghino 

P.  undulatus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  509. 
P.  depressus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  510. 

One  of  the  plates  we  found  has  the  rough  surface,  obscure 
figure,  two  pits  on  the  median  part  of  the  surface,  and 
marginal   piliferous   pits,   of   which   the 
first    two    features    are    characters    of 
P.  undulatus,  the  last  is  the  feature  of 
P.   depressus,   so    I    have  combined  the 
Fig.  133.  TWO  movable     two  species.     A  second  plate  does  not 
have  the  marginal  pits  but  is  otherwise 
the  same.     I  expect  considerable  variation  in  the  pattern 
on  plates  from  different  regions  of  the  carapace. 

Peltephilus  protervus  Ameghino 

P.  protervus,  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  509. 

This  species,  of  which  we  found  no  representative,  is 
very  large.     The  plates  of  the  type  have  two  pits  on  the 


PALAEOPELTIS 


205 


anterior  part  of  the  exposed  surface  and  none  on  the  margin. 
A  movable  plate  measures  41  mm.  long  by  22  mm.  wide. 
One  of  the  horn-like  plates  from  the  cephalic  shield  is 
35  mm.  long,  by  30  mm.  wide,  and  has  a  height  of  44  mm. 


GLYPTODONTIA 

This  suborder  is  most  sparingly  represented,  apparently 
on  account  of  unfavorable  habitat.  Ameghino  has  de- 
scribed a  few  fragments  of  the  carapaces  of  these  forms, 
making  the  genera,  Palaeopeltis,  and  Glyptatelus •,  both 
pre-Santa  Cruz  genera. 

Palaeopeltis  Ameghino 

Palaeopeltis  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  659. 

The  basis  of  this  genus  is  a  few  plates  of  a  glyptodon- 
like  animal  of  considerable  size,  but  the  plates  are  without 
ornamentation.  This  form  Ameghino  considers  inter- 
mediate between  glyptodonts  and  armadilloes.  I  feel 
that  there  is  too  little  of  the  skeleton  known-  to  justify  this 
conclusion,  especially  as  glyptodonts  of  a  considerably 
higher  grade  of  specialization  are  contemporaries  of  this 
form. 


Fig.  134.    P.  inornatus:  a  single  plate — natural  size. 


2O6 


THE  DESEADO  FORMATION  OF  PATAGONIA 


Palaeopeltis  inornatus  Ameghino 

P.  inornatus  Amegh.,  1895,  Bol.  Inst.  Geog.  Argcn.,  t.  15,  p.  659. 
P.  inornatus  Amegh.,  1897,  Bol.  Inst.  Gcog.  Argcn.,  t.  18,  p.  506. 

The  species  is  founded  on  four  plates  which  are  without 
ornamentation,  and  externally  smooth  except  for  numerous 
vascular  perforations.  They  are  of  considerable  size  and 
entirely  characteristic.  The  one  such  plate  which  we  found 
is  shown  in  fig.  134. 

Glyptatelus  Ameghino 

Glyptatelus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  1. 18,  p.  507. 

The  plates  of  the  carapace  are  similar  to  those  of  Pal- 
aeohoplophorus,  the  O-figure  being,  however,  nearer  the 
rear  of  each  plate,  and  the  number  of  radial  furrows  being 
smaller,  usually  six.  We  found  no  specimens  of  this  inter- 
esting form.  Ameghino  has  made  two  species,  G.  tatusinus 
and  G.  malaspinensis. 

Glyptatelus  tatusinus  Ameghino 

G.  tatusinus,  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  507. 

I  reproduce  Ameghino's  figure  of  this  species  which 
shows  all  that  is  known  of  the  form. 


-  I3S-  Four7i>lalcs— natural  size,  after 
Ameghino. 


GLYPTATELUS  207 

Glyptatelus  malaspinensis  Ameghino 

G.  malaspinensis  Amegh.,  1902,  Bol.  Acad.  Nac.  Cienc.,  Cordoba,  t.  17,  p.  50. 

This  species  is  described  (no  figure)  as  about  the  same 
size  as  the  preceding,  but  with  subordinate  figures  in  the 
central  O-figure,  and  also  outside  of  it.  A  dorsal  plate 
measures  26  mm.  long  by  20  mm.  wide. 

GRAVIGRADA 

Remains  of  this  suborder  are  almost  as  rare  as  those  of 
the  glyptodonts,  and  apparently  for  the  same  reason, 
unfavorable  habitat.  We  found  no  remains  of  this  group, 
but  Ameghino  has  described  a  skull  and  some  teeth  as 
belonging  to  this  group;  so,  in  order  to  present  a  complete 
view  of  the  Deseado  fauna,  I  give  a  digest  of  his  descrip- 
tions. 

Hapalops  antistis  Ameghino 

H.  antistis  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  505. 

The  species  is  based  on  a  skull,  not  figured,  of  which 
Ameghino  says:  the  size  is  small,  the  molars  are  compressed 
from  front  to  back,  and  gives  the  following  measurements: 

Length  of  cranium  from  front  of  max.  to  occ.  condyles  140  mm. 

Length  of  four  post,  molars  27  mm. 

Distance  from  front  of  max.  to  back  of  last  molar  48  mm. 

Octodontotherium  Ameghino 

Octodontotherium  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  656. 

The  genus  is  based  on  isolated  teeth,  each  a  mass  of 
dentine  surrounded  by  a  thin  layer  of  cement.  The  an- 
terior tooth  of  the  upper  jaw  is  caniniform,  the  first  molar 
ovoid  in  section,  the  last  molar  is  bilobed,  corresponding 
to  Pseudolestodon.  The  first  tooth  of  the  lower  jaw  is  also 
caniniform,  but  is  two-faced  as  a  result  of  wear.  The 
intermediate  upper  and  lower  molars  are  rectangular 
prisms  resembling  those  of  Chlamdotherium. 


208 


THE  DESEADO  FORMATION  OF  PATAGONIA 


Octodontotherium  grandis  Ameghino 

O.  grandis  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  656. 
O.  grandis  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  505. 

In  addition  to  the  above,  Ameghino  simply  gives  the 
following  measurements: 

First  upper  tooth,  ant. -post.  diam.  20  mm.,  trans,  diam.  13  mm.,  height  80  mm. 
First  lower  tooth,  ant. -post.  diam.  21  mm.,  trans,  diam.  16  mm.,  height  80  mm. 
Last  lower  tooth,  ant. -post.  diam.  28  mm.,  trans,  diam.  of  ant.  lobe  18  mm. 
Last  lower  tooth,  trans,  diam.  of  post,  lobe  16  mm.,  median  diam.  7  mm. 


Fig.  136.  A,  lower  molar,  side  view — natural  size;  B, 
lower  molar,  cross  section — natural  size;  C,  upper  molar, 
cross  section — natural  size,  after  Ameghino.  j  __, 

Octodontotherium  crassidens  Ameghino 

O.  crassidens  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  505. 

This  second  species  is  based  on  isolated  teeth  of  larger 
size  than  the  preceding,  with  measurements  as  follows: 

Upper  molar,  ant.-post.  diam.  26  mm.,  trans,  diam.  18  mm. 
Lower  molar,  ant.-post.  diam.,  26  mm.,  trans,  diam.  of  ant.  lobe  21  mm.,  trans, 
diam.  of  post,  lobe  16  mm. 


ORPHDDON  209 

Orphodon  Ameghino 

Orphodon  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  658. 
Orphodon  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  504. 

The  teeth  of  this  type  are  a  mass  of  dentine,  each  sur- 
rounded by  a  thin  layer  of  cement,  and  each  tooth  subcy- 
lindrical  in  section,  with  the  crown  worn  to  two  apposed 
oblique  planes.  The  genus  resembles  Ortotherium. 


Fig.  137-  Type — natural  size,  after 
Ameghino. 

Orphodon  hapaloides  Ameghino 

O.  hapaloides  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  658. 
O.  hapaloides  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  505. 

In  addition  to  the  above,  Ameghino  gives  a  figure,  here 
reproduced,  and  the  following  measurements:  Tooth, 
greatest  diam.  12  mm.,  lesser  diam.,  10  mm. 


14 


CHAPTER  XV 

MARSUPIALIA 

IN  OUR  collection,  the  marsupials  are  represented,  un- 
fortunately, by  but  a  few  specimens;  though  this  Deseado 
fauna  included,  as  is  shown  by  the  fragmentary  remains, 
a  wide  range  of  forms  from  Pilchenia,  the  size  of  a  mouse, 
up  to  the  bear-sized  Proborhyaena.  The  small  forms  were 
probably  insectivorous,  while  the  larger  forms  took  the 
place  of  the  carnivors,  the  absence  of  true  Carnivom  being 
one  of  the  striking  features  of  the  fauna  of  South  America 
during  earlier  Tertiary  times. 

The  treatment  of  these  forms  has  been  as  varied  as  their 
sizes.  Ameghino,  with  his  idea  that  the  Casamayor  and 
Deseado  beds  were  Cretaceous  in  age,  groups  the  larger 
forms  as  a  suborder,  Sparassodonta,  and  considers  them 
ancestral  to  the  Creodonta;  while  the  small  forms  make  up 
his  Sarcobora  which  he  considered  ancestral  on  one  side  to 
the  rodents,  on  the  other  to  the  diprotodont  marsupials. 
Sinclair,  after  showing  the  marked  similarity  of  the  Spar- 
assodonta  to  the  polyprotodont  marsupials,  especially  the 
genus  Thylacynus,  abandons  that  term  and  puts  them  in 
the  family  Thylacynidae  along  with  the  Australian  forms; 
the  Microbiotheridae  he  finds  similar  to  opossums  and 
puts  in  the  family  Didelphidae;  while  the  remaining  small 
diprotodont  forms  he  associates  with  Caenolestes,  and  using 
Ameghino's  families  as  subfamilies  makes  three  divisions 
of  the  family,  'Palaeothentinae,  Garzoninae,  andAbderitinae. 
Matthew  finds  the  sparassoclonts  to  be  true  marsupials, 
and  without  phylogenetic  relationship  with  the  creodonts. 
Gregory  diagrams  the  sparassodonts  as  coming  from  gener- 
alized didelphids  and  derives  them  from  the  same  line  as 
the  Australian  poly  pro  todonts;  while  the  small  caenoles- 


MARSUPIALIA  211 

toids  represent  a  line  of  descent  from  some  still  earlier 
generalized  poly  pro  todonts  and  a  separate  stem  from  the 
Australian  diprotodonts. 

Sinclair  has  had  the  most  complete  material  on  which 
to  work,  and  with  his  general  grouping  I  have  come  to 
agree.  This  recognizes  three  divisions  of  South  American 
Marsupials,  the  Didelphidae,  representatives  of  which  have 
not  yet  been  found  in  the  Deseado,  though  occurring  in 
both  the  earlier  and  later  formations;  the  Caenolestidae 
represented  today  by  Caenolestes,  the  only  survivor  of 
the  South  American  diprotodonts;  and  the  Borhyaenidae 
( =  Thylacynidae  of  Sinclair  this  name  having  been  used  to 
indicate  a  much  nearer  relationship  to  the  Australian  Thy- 
lacynns  than  I  feel  is  warranted),  which  includes  a  large 
range  of  medium  to  large  sized  animals  ranging  from  the 
Casamayor  formation  throught  the  Santa  Cruz  beds. 

The  locality  from  which  these  marsupials  emigrated  to 
South  America  and  the  time  of  their  arrival  is  not  yet 
agreed  upon,  and  can  not  be  settled  until  much  more  com- 
plete material  is  discovered  in  the  Casamayor  formation. 
I  feel,  however,  that  the  three  groups  were  separate  when 
they  entered  South  America. 

Borhyaenidae 

Ameghino  has  grouped  in  this  family  a  considerable 
number  of  genera  of  powerful,  wolf-like  carnivorous 
marsupials,  characterized  by  a  dental  formula  433  \  *  ** 
heavy  heads,  short  limbs  with  usually  five  semidigitigrade 
toes.  The  genera  are  mostly  distinguished  by  the  relative 
development  of  the  protocone  on  the  upper  molars  and  the 

*  There  is  a  discussion  as  to  the  homologies  of  the  premolars  of  marsupials 
and  placental  mammals,  the  one  proposition  being  that  marsupials  have  three 
premolars  and  four  molars,  the  other  that  they  have  four  premolars  and  three 
molars  as  in  placentals.  The  evidence  is  not  conclusive  as  to  either  proposi- 
tion, but  in  this  paper  I  have  designated  these  teeth  along  the  latter  line  of 
thought. 


212 


THE  DESEADO  FORMATION  OF  PATAGONIA 


talonid  on  the  lower  ones.  Figure  138  gives  a  typical  mar- 
supial upper  molar  2  and  a  lower  molar  2  to  show  the  sense 
in  which  these  terms  are  used.  The  Santa  Cruz  genera 
are  the  best  known  and  I  therefore  use  them  as  a  basis 
for  comparison  with  the  less  known  Deseado  forms,  of 
which  \ve  found  but  the  one  genus  Pharsophorus  at  all 
abundant.  In  addition  to  this,  Ameghino  has  reported  a 
gigantic  form  designated  Proborhyaena.  The  following 
table  indicates  the  relationships  of  the  best  known  genera. 


AGE 

FORMULA 

PROTOCONE 

UPPER  MOLAR 
3 

TALONID  ON 
LOWER  MO- 
LAR 3 

SYMPHYSIS 

Cladosictis 

Santa  Cruz 

4143 

on  pm.  4~m.  3 

Protocone 
Paracone  vesti- 
gal 
Metaconc 
Ant.  ext.  style 

Small  basin 
with    one 
post,  cusp 

Ligamentous 

3143 

Amphiprovivvera 

Santa  Cruz 

4143 
3143 

on  pm.  4-m.  3 

Protocone 
Paracone 
Ant.  ext.  style 

Basin       with 
two      post, 
cusps 

Ligamentous 

Prothylacynus 

Santa  Cruz 

4143 

on  pm.4tn.  i 

Protocone    ves- 
tigal 
Metacone 

Small      basin 
with       one 
post,    cusp 

Fused 

3143 

Borhyaena 

Santa  Cruz 

3143 

vestical 

Paracone 
Ant.  ext.  style 

No  basin 
One  post.cusp 

Fused 

3143 

Pharsophorus 

Deseado 

I  4  3 

vestigal 

Protocone    ves- 
tigal 
Paracone 
Ant.  ext.  style 

Very  small 
No  basin 
One  post.cusp 

Ligamentous 

143 

Proborhyaena 

Deseado 

Fused 

I  4  3 

From  the  foregoing,  it  will  appear  that  Pharsophorus 
approaches  Borhyaena  and  Prothylacynus  in  the  structure 
of  its  upper  molars,  being,  however,  nearer  to  the  former, 
and  the  same  is  true  of  the  structure  of  the  talonid;  but 
Pharsophorus  differs  markedly  from  both  in  retaining  the 
metaconid  as  a  small  cusp  on  the  side  of  the  protoconid 
on  all  of  the  lower  molars;  also  in  the  extremely  small  size 


PHARSOPHORUS 


213 


of  the  talonid  of  the  lower  molars,  which  in  Pharsophorus 
have  no  basin  and  consist  of  a  single  cusp;  and,  lastly,  in 
the  symphysis  of  the  lower  jaws  being  ligamentous,  whereas 
in  the  two  preceding  genera,  it  is  fused.  Pharsophorus 
is  probably  ancestral  to  Borhyaena.  In  the  case  of  Probor- 
hyaena,  only  a  mandible,  with  the  canine  and  premolars 
3  and  4  intact,  has  been  found.  The  fourth  premolar  is 
more  reduced  than  in  other  genera,  but,  until  more  teeth 
are  known,  its  affinities  can  not  be  at  all  closely  determined. 


U.m. 

Fig.  138.  Diagram  of  a  generalized  upper  molar,  U.m.,  and  a  lower  molar,  L.m.,  of  Borhynidae; 
a.s.,  ant.  style;  hid.,  hypoconulid;  ml.,  metacone;  mtd.,  metaconid;  pa.,  paracone;  pad.,  paraconid; 
Pr.,  protocone;  prd.,  protoconid;  Id.,  talonid. 

Pharsophorus  Ameghino 

Pharspohorus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  502. 

The  genus  was  founded  on  a  lower  jaw  with  premolar 
3  to  molar  3  in  position.  We  found  beside  the  above  an 
upper  jaw  with  premolar  3,  and  molars  2  and  3  complete 
while  premolar  4  and  molar  I  are  more  or  less  fragmentary ; 
from  which  the  following  generic  characters  may  be  made 
out.  The  incisors  are  tiny;  the  canine  very  large,  equal 
to  that  of  Borhyaena;  the  upper  and  lower  premolars  pro- 
gressively smaller  from  front  to  back.  Upper  premolar  3 
is  a  simple  two-rooted  tooth,  the  crown  consisting  of  a 
single  blunt  central  cusp.  On  the  upper  molars  the  proto- 
cone is  not  developed  as  a  cusp,  though  the  third  inner  root 


214  THE  DESEADO  FORMATION  OF  PATAGONIA 

is  present  and  carries  a  rounded  shelf.  The  paracone  is 
the  chief  cusp,  and  is  developed  as  a  high  central  pointed 
denticle.  The  metacone  is  not  developed  as  a  cusp,  but  is 
represented  by  a  long  slanting  ridge  to  the  rear,  the  apex 
of  which  has  been  fused  to  the  paracone.  The  last  upper 
molar  is  better  developed  than  in  most  Santa  Cruz  genera, 
consisting  of  a  high  median  cusp,  the  paracone;  a  small 
anterior  cusp,  the  anterior  external  style;  and  a  shelf-like 
posterior  cusp,  the  protocone.  Lower  premolars  1-3  are 
simple  two-rooted  teeth,  each  carrying  a  single  cusp  on 
the  crown.  The  fourth  premolar  carries  a  well  marked 
paraconid  in  front,  a  large  median  protoconid  on  the  rear 
of  which  is  a  tiny  metaconulid ;  and  a  tiny  talonid  or  heel 
wrhich  is  without  a  basin  and  consists  of  a  single  tiny  cusp. 
The  molars  are  all  of  the  same  character  as  the  last  pre- 
molar. The  lower  jaws  are  united  by  a  ligamentous  sym- 
physis. 

Ameghino  distinguished  four  species,  P.  lacerans,  P. 
tenax,  P.  mitis,  and  P.  tennis,  in  the  order  of  their  size. 
The  last  two  are  but  little  known  but  are  quite  certainly 
another  genus. 

Pharsophorus  lacerans  Ameghino 

P.  lacerans  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  503. 

The  species  was  founded  on  a  lower  jaw  with  the  roots 
of  the  incisors,  canine,  and  first  two  premolars,  and  with 
the  remaining  teeth  intact.  We  did  not  find  the  species, 


Fig.  139.  Left  mandible — 1/2  natural  size,  after  Ameghino. 


PHARSOPHORUS 


215 


so    I    have   reproduced   Ameghino's   figure   and   give   his 
measurements. 

Lower  dentition,  length  incisor  I  to  molar  3  114  mm. 

Lower  dentition,  length  premolar  I  to  molar  3  90  mm. 

Lower  dentition,  height  of  mandible  under  pm.  4  38  mm. 

Pharsophorus  tenax  Ameghino 

P.  tenax  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  504. 

The  species  was  based  on  a  fourth  premolar  which  was 
10  mm.  long  as  compared  with  13  mm.  in  P.  lacerans.  We 
found  on  the  Chico  del 
Chubut,  west  of  Puerto 
Visser,  both  an  upper  and 
lower  jaw  belonging  to  this 
species,  which  give  us  the 
knowledge  of  the  upper  den- 
tition for  the  genus.  The 
species  is  distinguished  by 

the    Smaller   Size,    relatively 

heavy    jaws,    and    plump 

teeth,  indicating  a  heavier  built  animal  than  P.  lacerans. 

The  following  measurements  distinguish  the  species. 


Fig.  140.    Lef  t  upper  jaw—  1/2  natural  size;  A, 
molars  3  and  4  from  above;  B,  molars  from  ex- 


Fig.  141.  Right  mandible — 1/2  natural  size. 


SPECIMEN  3192 

Upper  dentition,  length  premolar  I  to  molar  3 
Upper  dentition,  premolar  3,  length 
Upper  dentition,  molar  I,  length 
Upper  dentition,  molar  2,  length 
Upper  dentition,  molar  3,  length 


76       mm. 

10.5  mm.,  width    6       mm. 

11.5  mm.,  width    8.5  mm. 

12       mm.,  width    9       mm. 

.55mm.,  width  12        mm. 


216  THE  DESEADO  FORMATION  OF  PATAGONIA 

SPECIMEN  3004 
Lower  dentition 

Distance  from  premolar  I  to  molar  3  76  mm. 

Molar  i,  length  II   mm.,  width          6  mm. 

Molar  2,  length  13  mm.,  width          6  mm. 

Molar  3,  length  13  mm.,  width          7  mm. 

Height  of  mandible  under  premolar  4  30  mm. 

Notogale  gen.  nov. 

This  genus  is  proposed  for  the  species  designated  ?Phar- 
sophorus  mills  by  Ameghino  (should  probably  include  ?Phar- 
sophorus  tennis  which  however  never  having  been  figured 
and  not  found  in  our  collection  I  cannot  definitely  place). 
While  the  upper  teeth  have  the  same  general  character 
as  Pharsophorus,  they  are  much  more  compressed  and  tren- 
chant. Upper  molar  2  is  similar  to  that  of  Pharasophorus 
in  having  the  protocone  reduced,  and  the  metacone  repre- 
sented by  a  long  sloping  ridge.  The  last  molar  is  also 
similar  in  having  the  antero-external  style,  the  developed 
paracone,  but  the  protocone  is  much  less  developed,  appear- 
ing only  as  a  ridge.  In  the  lower  teeth,  however,  there  is 
a  marked  difference,  in  that  the  metaconid  is  lacking  on 
molars,  while  the  talonid  is  developed  into  a  small  basin 
with  a  single  cusp  on  the  posterior  margin.  This  genus 
seems  to  be  closest  to  the  Santa  Cruz  genus  Cladosictis. 

Notogale  mitis  Ameghino 

?  Pharsophorus  mitis,   1897,    Bol.   Inst.  Geog.   Argen.,  t. 
18,  p.  504. 

Ameghino  briefly  describes,  without  a  figure,  a  species 
in  which  premolar  4  and  molar  3  together  measure  14  mm. 

o  p'C^F^    I  have  assigned  to  this  two  specimens,  the 
{./      (js      P  one  with  pm.  2  incomplete,  pm.  3  complete, 

Fig.  142.  upper  and  m.  2  also  complete.    These  teeth  meas- 

molars  2  to  4 — nat- 

ure  the  same  as  Ameghino' s  and  I  think  are 
the  same..  There  is  also  a  fragment  of  the  upper  jaw  with 
molars  2  and  3,  though  imperfect.  From  these  it  appears 


NOTOGALE 


2I7 


that  we  have  to  do  with  an  animal  not  only  smaller  than 
the  preceding,  but  on  much  slenderer  lines.  The  following 
are  the  measurements  of  the  two  specimens. 


SPECIMEN  3117 

Upper  dentition,  molar  2,  length 
Upper  dentition,  molar  3,  length 

SPECIMEN  3060 

Lower  dentition,  premolar  3,  length 
Lower  dentition,  molar  2,  length 


8  mm.,  width 
2  mm.,  width 


6  mm.,  width 

7  mm.,  width 


6  mm. 
6  mm. 


2.5  mm. 
4  mm. 


Fig.  143.  Left  mandible — natural  size. 


Notogale  tenuis  Ameghino 

?  Pharsophorus  tenuis  Amegh.,  1897,  Bol.  Inst.  Geog.,  Argen.,  t.  18,  p.  504. 

This  species  was  founded  by  Ameghino  on  a  single  lower 
premolar  3  which  is  3  mm.  in  length.  No  further  descrip- 
tion is  given  and  no  figure. 

Proborhyaena  Ameghino 

Proborhyaena  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  501. 

The  genus  is  founded  on  a  large  lower  jaw  carrying  the 
canine  and  premolars  3  and  4  and  roots  or  alveoli  for  the 
other  teeth.  It  is  the  largest  carnivor  recorded  from 
Patagonia,  and  as  large  as  a  small  bear.  It  is  not  possible 


2l8  THE  DESEADO  FORMATION  OF  PATAGONIA 

to  place  its  exact  relationships,  for  the  most  essential  teeth 
are  wanting,  but  it  is  certainly  a  distinct  genus  as  indicated 
by  the  reduced  size  of  premolar  4  and  the  plump  character 
of  the  teeth. 

Proborhyaena  gigantea  Ameghino 

P.  gigantea  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  501. 

We  found  no  specimens  of  this  great  carnivor,  so  I  am 
reproducing    Ameghino's  figure  and  measurements.     The 


Fig.  144.  Right  mandible — 1/2  natural  size,  after  Ameghino. 

heavy  canine  is  channeled  on  the  sides  and  much  worn  on 
the  posterior  face.  Premolar  3  is  a  plump  tooth,  its  crown 
consisting  mostly  of  a  single  median  cusp,  but  with  a  small 
heel  behind,  and,  strikingly  enough,  premolar  4  is  a  smaller 
and  simpler  tooth  with  a  single  cusp. 

MEASUREMENTS 

Lower  dentition,  canine,  antero-posterior  diameter  30  mm. 

Lower  dentition,  canine,  transverse  diameter  20  mm. 

Lower  dentition,  premolar  I  to  molar  3  145  mm. 

Lower  dentition,  height  of  mandible  under  pm.  4  60  mm. 


CAENOLESTIDAE  219 

Proborhyaena  antiqua  Ameghino 

?  Borhyaena  antiqua  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  655. 
Proborhyaena  antiqua  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  5012. 

This  species  is  known  only  by  a  single  canine  100  mm. 
long,  of  which  but  15  mm.  belongs  to  the  crown.  Its 
antero-posterior  diameter  is  14  mm.,  the  transverse  12  mm. 
It  seems  to  me  very  doubtful  whether  this  is  a  valid  species. 

Caenolestidae 

This  family,  based  on  the  living  genus  Caenolestes,  is 
represented  in  Tertiary  times  in  Patagonia  by  three  sub- 
divisions, Palaeothentinae,  Garzoninae,  and  Abderitinae. 
While  diprotodonts,  as  far  as  known,  the  family  is  in  strong 
contrast  to  the  Australian  diprotodonts  in  that  there  is  no 
sign  of  syndactylism  in  the  pes.  The  American  forms  are 
characterized  by  four  subequal  upper  incisors,  a  normal 
canine,  the  first  three  premolars  vestigal,  while  the  fourth 
is  either  normal  or  enlarged  into  a  sectorial  tooth.  The 
three  molars  are  progressively  smaller  from  the  front  back. 
The  first  lower  incisor  is  greatly  enlarged  and  procumbrent, 
the  remaining  incisors,  the  canine,  and  the  anterior  pre- 
molars being  vestigal  though  usually  present.  Premolar 
4  is  enlarged  and  sectorial  in  most  genera,  and  the  molars 
as  in  the  upper  jaw  progressively  smaller. 

For  the  practical  purposes  of  this  paper  the  subfamilies 
are  distinguished  as  follows: 

Caenolestinae,  lower  pm.  4  not  developed  into  a  sectorial  tooth. 
Palaeothentinae,  lower  pm.  4  is  developed  into  a  sectorial  tooth. 
Abderitinae,  lower  pm.  4  is  developed  into  a  sectorial  tooth  and  striated. 

Palaeothentinae  Sinclair. 
( =  Epanorthidae  Ameghino) 

This  group  or  subfamily  was  established  to  hold  several 
genera  of  tiny  marsupials  with  the  dental  formula  jTrf-; 
the  lower  fourth  premolar  enlarged  into  a  sectorial  tooth; 


220  THE  DESEADO  FORMATION  OF  PATAGONIA 

and  the  molars  small  and  buno-lophodont.  From  the 
Deseado  beds  but  one  genus  of  this  subdivision  has  been 
found,  Palaeothentes,  designated  by  Ameghino  first  Epan- 
orthus ^  then  later  Palaepanorthus,  but  as  I  can  see  no  reason 
for  distinguishing  the  Deseado  species  of  the  genus  from 
those  of  the  Santa  Cruz,  I  have  retained  the  name  Palaeo- 
thentes. 

The  genera  of  this  subfamily  are  distinguished  as  follows: 

LOWER  THIRD  PREMOLAR 

Palaeothentes  2-rooted,  fairly  large,  equals  pm.  4  in  height. 
Pilchenia  2-rooted,  moderate  size  nearly  equals  pm.  4  in  height. 
Callomenus  2-rooted,  small  size  much  lower  than  pm.  4. 
Decastris,  i -rooted,  vestigal. 

Palaeothentes  (Moreno)  Ameghino 

Palaeothentes  Moreno,  1882^  Patagonia,  Resto  de  tin  Continente  hoy  sub- 

mergido,  p.  22,  (nomen  nudum). 
Palaeothentes  (Moreno)  Ameghino,  1887,  Enum.  Sist.  Espesies  Mamif.  Fos, 

Patagonia,  p.  5. 

Epanorthus  Ameghino,  1889,  Act.  Acad.  Nac.  Cienc.  Cordoba,  t.  6,  p.  271. 
Epanorthus  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  500.  (nudum). 
Palaepanorthus  Amegh.,  1901,  Anal.  Soc.  Cienc.  Argen.,  t.  51,  p.  77,  (nomen). 
Palaepanorthus  Amegh.,  1902,  Bol.  Acad.  Nac.  Cienc.  Cordoba,  t.  18,  p.  123. 
Palaepanorthus  Amegh.,  1903,  Anal.  Mus.  Nac.  Buenos  Aires,  t.  9,  (ser.  3,  t. 

2)  p.  239. 

Among  the  Santa  Cruz  specimens,  this  genus  is  distin- 
guished by  having  in  the  lower  jaw  the  large  first  incisor, 
then  five  vestigal  teeth,  followed  by  a  two-rooted,  though 
somewhat  reduced,  third  premolar,  next  the  enlarged 
fourth  premolar,  making  the  sectorial  tooth,  and  lastly 
three  buno-lophodont  molars. 

There  is  considerable  confusion  as  to  the  use  of  the  gen- 
eric name.  Moreno  designated  the  first  specimen,  Palaeo- 
thentes, without  a  description ;  then  Ameghino  used  this  term 
describing  the  species;  later  Ameghino  thinking  that  the 
name  Palaeothentes  was  the  same  as  Palaeothentis  proposed 
the  name,  Epanorthus,  using  this  for  the  first  description 


PALAEOTHENTES  221 

of  the  Deseado  species.  Later,  however,  he  changed  this 
for  Palaepanothus.  As  I  can  see  no  generic  differences 
between  the  Deseado  and  Santa  Cruz  species,  I  shall  follow 
Sinclair  in  using  the  generic  term  Palaeothentes. 

Palaeothentes  chubutensis  Ameghino 

Epanorthus  chubutensis  Amegh.,  1897,  Bol.  Inst.  Geog.  Argen.,  t.  18,  p.  500. 
Palaepanorthus  chubutensis  Amegh.,  1901,  Anal.  Soc.  Cienc.  Argen.,  t.  51,  p. 

77- 
Palaepanorthus  chubutensis  Amegh.,  1902,  Bol.  Acad.  Nac.  Cienc.  Cordoba, 

t.  18,  p.  123. 
Palaepanorthus  chubutensis  Amegh.,  1903,  Anal.  Mus.  Nac.  B.  A.,  t.  9  (ser. 

3,  t.  2)  p.  239. 

The  species  is  founded  on  a  tiny  mandible  with  premolar 
3-molar  3,  on  which  the   third  premolar,  while  reduced, 


Fig.  145.  Right  mandible — 2  times  natural  size,  after  Ameghino. 

has  two  roots  and  reaches  the  height  of  the  fourth  premolar, 
being  in  about  the  same  stage  of  development  as  the  Santa 
Cruz  species.  As  we  found  no  specimens  of  this  species  I 
reproduce  Ameghino's  figure  and  measurements. 

Lower  dentition,  premolar  3  to  molar  3  19  mm. 

Lower  dentition,  height  under  premolar  4  12  mm. 

Pilchenia  Ameghino 

Pilchenia  Ameghino,  1903,  Anal.  Mus.  Nac.  Buenos  Aires,  ser.  3,  t.  2,  p.  128. 
Pilchenia  Ameghino,  1904,  Anal.  Soc.  Cienc.  Rep.  Argen.,  t.  58,  p.  259. 

This  genus  was  founded  on  a  single  lower  molar  which, 
in  the  light  of  the  specimen  we  found,  I  take  to  be  the  third 


222  THE  DESEADO  FORMATION  OF  PATAGONIA 

or  last.  Our  specimen  shows  pm.  3  and  4  and  the  three 
molars.  The  third  premolar  is  a  small  two-rooted  tooth 
with  a  simple  crown  and  no  heel.  Premolar  4  is  an  en- 
larged sectorial  tooth,  the  anterior  part  consisting  of  two 
cusps,  closely  set  near  the  median  line,  with  an  incipient 
cusp  on  the  inner  face  of  the  large  anterior  cusp.  The 
posterior  part  of  this  tooth  is  arranged  as  a  typical  talonid, 
with  one  internal  and  two  external  cusps  on  the  margin  of 
a  shallow  inclosed  basin.  On  the  rear  of  the  tooth  is  a 
small  crescent-like  cingulum,  which  occurs  in  the  same  place 
on  molars  I  and  2,  but  is  lacking  on  molar  3.  This  is  a 
characteristic  feature  of  the  genus.  On  the  anterior  part 
of  the  molars  is  developed  a  sort  of  trigonid  of  small  size, 
and  the  cusps  are  indistinct.  The  posterior  portion  of  each 
molar  is  a  large  talonid  with  a  shallow  basin  surrounded  by 
a  low  wall  on  which  are  three  tiny  cups  (the  entoconid, 
hypoconid,  and  hypoconulid). 

Pilchenia  lucina  Ameghino 

P.  lucina  Amegh.,  1903,  Anal.  Mus.  Nac.  B.  A.,  ser.  3,  t.  2,  p.  128. 
P.  lucina  Amegh.,  1904,  Anal.  Soc.  Cienc.  Rep.  Argen.,  t.  58,  p.  259. 

In  the  Deseado  beds,  on  the  Chico  del  Chubut  River, 
west  of  Puerto  Visser,  we  found  a  single  specimen  of  this 


Fig.  146.  Left  mandible  with  premolar  3  to  molar  4 — 4  times 
natural  size. 

species  which  agrees  with  the  single  tooth  figured  by  Ameg- 
hino as  the  type,  and  which  I  interpret  as  molar  3.  The 
description  is  given  under  the  genus,  the  measurements 
are  as  follows: 


CALLOMENUS 


223 


SPECIMEN  No.  3110 

Lower  dentition,  distance  from  premolar  3  to  molar  3  14  mm. 

Lower  dentition,  premolar  3,  length  2  mm.,  width  .75  mm. 

Lower  dentition,  premolar  4,  length  5  mm.,  width  2.5  mm. 

Lower  dentition,  molar  I,  length  3  mm.,  width  2  mm. 

Lower  dentition,  molar  2,  length  2.5  mm.,  width  2  mm. 

Lower  dentition,  molar  3,  length  2  mm.,  width  1.75  mm. 

Lower  dentition,  height  under  pm.  4  5  mm. 

Callomenus  Ameghino 

Callomenus  Amegh.,  1891,  Neuvos  Restos  Mamif.  Fos.  Patagonia  Austral,  p. 

20. 
Callomenus  Sinclair,  1901-6  Princeton  Patag.  Expeditions,  vol.  4,  p.  434. 

This  genus  has  not  been  previously  reported  from  the 
Deseado  beds,  but  we  found  a  tiny  lower  jaw  with  three 
teeth  to  represent  it.  The  genus  is  distinguished  by  pre- 
molar 3  being  two-rooted,  but  so  small  as  not  to  attain  the 
height  of  premolar  4. 

Callomenus  praecursor  sp.  nov. 

The  type  is  specimen  No.  3020,  a  fragmentary  mandible 
with  premolars  3  and  4  and  molar  i  in  place.  Pm.  3  is 


Fig.  147.  Left  mandible  with  premolar  3 
to  molar  2 — 4  times  natural  size. 


Fig.  148.    Left  mandible  internal  side — 4  times 
natural  size. 


two-rooted,  but  so  small  as  to  be  entirely  overshadowed 
by  the  succeeding  pm.  4,  hardly  reaching  a  half  the  height 
of  that  tooth.  On  the  last  premolar  and  the  first  molar, 
the  cusps  are  arranged  in  a  trigonid  in  front  and  a  talonid 
behind,  the  cusps  being  joined  by  thick  ridges,  making  two 
connecting  crescents. 


224  THE  DESEADO  FORMATION  OF  PATAGONIA 

MEASUREMENTS,  SPECIMEN  3020 

Lower  dentition,  premolar  3,  length  i    mm. 

Lower  dentition,  premolar  4,  length  5  mm.,  width  2  mm. 

Lower  dentition,  molar  i,  length  4  mm.,  width  2  mm. 

Lower  dentition,  height  under  pm.  4  6.5  mm. 

Caenolestinae 

The  subfamily  is  distinguished  by  the  formula  4133, 
pm.  4  not  being  enlarged,  and  the  lower  molars  being 
(ul)crculo-sectorial.  In  the  Descado  formation  this  group 
is  only  represented  by  a  single  species,  based  on  a  single 
tooth  found  by  Ameghino. 

Pseudhalmarhiphus  guaraniticus  Ameghino 

P.  guaraniticus  Amegh.,  1903,  Anal.  Mus.  Nac.  Buenos  Aires,  ser.  3,  t.  2,  p. 
83- 

Based  on  a  single  tooth,  similar  to  those  found  in  the 
Santa  Cruz. 

Abderitinae 

The  subfamily  is  distinguished  by  the  formula  *  \  ?2*3 , 
the  fourth  premolar  being  enlarged  into  a  sectorial  tooth 
on  the  sides  of  which  are  vertical  striae.  The  molars  are 
buno-lophodont.  The  Deseado  has  yielded  only  a  tiny 
form,  designated  Parabdcrites,  which  differs  from  the  Santa 
Cruz  genus  Abderiles  in  pm.  4,  the  same  shape,  by  with 
few  to  no  striae  on  its  sides. 

Parabderites  minusculus  Ameghino 

P.  minusculus  Amegh.,  1902,  Bol.  Acad.  Nac.  Cienc.  Cordoba,  t.  17,  p.  43. 

The  species  as  described  by  Ameghino  is  based  on  a 
lower  jaw  with  pm.  3  to  m.  3.  The  specific  character  is 
the  lack  of  striae  on  pm.  4.  No  figure  is  given  but  the 
following  measurements  indicate  the  size. 

Lower  dentition,  premolar  3  to  molar  3  9   mm. 

Lower  dentition,  height  of  mandible  under  pm.  4  4  mm. 


CHAPTER   XVI 

BIRDS 

IN  THE  Deseado  beds,  birds  occur  in  small  numbers, 
Ameghino  having  described  four  species.  The  remains 
are  generally  found  as  isolated  bones,  and  it  is  hard  to  as- 
sociate the  separate  finds  one  with  another.  Beside  this 
there  are  very  few  birds  of  the  early  Tertiary  so  known, 
as  to  make  separate  bones  indicate  the  family  or  generic 
relationships. 

In  the  overlying  Patagonian  beds,  a  considerable  number 
of  species  have  been  found,  mostly  of  penguin-like  birds, 
the  various  genera  and  species  being  based  on  the  tarso- 
metatarsus.  On  the  upper  surface  of  the  Deseado,  we 
found  several  bones  of  this  penguin-like  type,  but  in  all 
cases  they  were  washed  out,  so  that  I  have  considered  them 
as  having  come  from  the  Patagonian. 

However,  we  found  eight  specimens  of  birds  in  place  in 
the  Deseado,  most  of  which  are  clearly  land  birds  and 
belong  to  genera  which  are  closely  related  to  genera  of 
the  Santa  Cruz,  especially  the  two  genera  Phororhacus 
and  Pelecyornis,  and  of  sizes  equal  to  the  largest  represen- 
tatives of  the  two  genera. 

Phororhacus  Ameghino 

Phororhacus  Amegh.,  1887,  Bol.  Mus.  La  Plata,  t.  I,  p.  24. 

Phororhacus  Amegh.,  1889,  Act.  Acad.  Nac.  Cienc.  Cordoba,  t.  VI,  p.  659. 

Phororhacus  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  10  of  separate. 

This  is  a  group  of  large  land  birds,  comparable  in  size  to 
the  great  moasof  New  Zealand  which  apparently  arose,  flour- 
ished, and  died  out  in  South  America.  In  the  Santa  Cruz 
they  were  abundant,  the  best  known  form  being  P.  inflatus, 
a  bird  some  six  feet  high ;  while  the  largest,  P.  longissimus, 

15 


226  THE  DESEADO  FORMATION  OF  PATAGONIA 

had  a  head  nearly  twice  as  long  and  limb  bones  half  again 
as  large  as  this  species;  so  that  it  represented  a  bird  nine 
to  ten  feet  high.  Previously  but  one  specimen  of  this  type, 
a  part  of  a  mandible,  has  been  found  in  the  Deseado  beds. 
We  were  fortunate  enough  to  find  the  greater  part  of  a 
femur,  indicating  a  bird  equal  to  the  largest  of  those  in  the 
Santa  Cruz.  There  are  also  toe  bones  of  Phororachus  of 
a  size  about  the  same  as  P.  inflatus. 

A  host  of  names,  generic  and  specific,  have  been  given  to 
the  individual  bones  of  the  birds  of  this  type,  but  Ameghino, 
in  studying  the  birds  of  the  Santa  Cruz,  brought  them 
all  together  under  the  single  genus  Phororhacus.  (See  Bol. 
Inst.  Geog.  Argen.,  1895,  t.  15.)  Referring  to  the  single 
bone  in  the  Deseado,  however,  he  gave  it  a  new  generic 
name  Physornis,  which  differs  from  Phororhacus  only  in 
the  lower  jaw  being  more  convex,  but  should  stand  until 
better  material  has  been  found  to  establish  whether  it 
differs  enough  to  be  entitled  to  generic  independence. 

Physornis  fortis  Ameghino. 

P.  fortis  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  576. 

Under  this  specific  name  Ameghino  describes  a  part  of  the 
lower  jaw  150  mm.  long  which  he  says  equals  in  size  Phoror- 
hacus longissimus,  and  differs  only  in  the  greater  convexity 
of  the  mandible.  Our  specimen  is  a  femur,  apparently  of 
the  same  bird,  being  of  the  type  of  Phororhacus  and  about 
the  size  of  P.  longissimus;  so  I  have  placed  it  in  this  species. 

This  femur  is  of  large  size,  moderate  length,  and  has  a 
shaft  subcylindrical  in  section.  The  distal  end  is  expanded 
and  the  condyles  are  flattened,  the  inner  one  being  the  wider, 
the  outer  condylc  being  narrower  and  the  external  margin 
projecting  to  make  a  high  ridge.  The  pit  on  the  posterior 
side  of  the  shaft  just  above  the  condyles  is  unusually  deep 
and  of  large  size.  On  the  anterior  side  there  extends  from 
either  condyle  a  low  marginal  ridge  which  soon  fades  into 


PHYSORNIS  FORTIS 


227 


Fig.  149.  Right  femur,  back  view — 1/2  natural  size. 


228 


THE  DESEADO  FORMATION  OF  PATAGONIA 


the  contour  of  the  shaft.  Between  these  ridges  there  is  a 
wide  shallow  furrow  which  also  loses  itself  above  in  the  con- 
vex surface  of  the  shaft. 


MEASUREMENTS 


Femur,  least  diam.  of  the  shaft 
Femur,  diameter  across  the  condules 


58  mm. 
148  mm. 


Physornis  sp.? 

Two  phalanges  of  a  size  too  small  to  belong  to  the  above 
species  represent  a  second  smaller  bird  of  this  type,  about 
equal  in  size  to  Phororhacus  infiatus.  I  give  a  figure  of 
one  toe  but  would  wait  for  more  typical  material  before 
establishing  a  species. 


Fig.  150.  Proximal 
phalanx  of  Physornis 
sp? — natural  size. 


Fig.  151.  Loxornis 
cliyus,  lower  end  of 
tibio-tarsus,  after  Ame- 
ghino — natural  size. 


Loxornis  Ameghino 

Loxornis  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  595. 

Another  group  of  bones,  which  we  found  with  consider- 
able frequency,  have  the  same  features  as  Pelecyornis  of 
the  Santa  Cruz.  Ameghino  has  described  but  the  lower 
end  of  a  tibio-tarsus  which  can  be  associated  with  these 
bones  and  to  it  gave  the  name  Loxornis.  I  can  not  find 


LOXORNIS  229 

much  variation  from  Pelecyornis  except  that  the  coracoid 
is  considerably  shorter  and  wider,  and  there  is  a  slight 
variation  in  the  lower  end  of  the  ti bio- tarsus.  These  then 
are  the  bases  of  the  generic  name. 

Loxornis  clivus  Ameghino 

L.  clivus  Amegh.,  1895,  Bol.  Inst.  Geog.  Argen.,  t.  15,  p.  595. 

Under  this  name  Ameghino  has  described  the  lower  end 
of  a  tibio-tarsus,  a  figure  of  which  I  reproduce  here.  This 
is  of  a  size  to  complete  the  tibio-tarsus  which  we  found, 
lacking  the  lower  end,  and  agrees  in  size  with  the  other 


Fig.  152.  Humerus —  Fig.  153.  Sternum,  thin  parts  lack-  Fig.  154.  Coracoid — 

1/2  natural  size.  ing — 1/2  natural  size.  1/2  natural  size. 

bones  which  we  found,  so  that  I  shall  describe  my  material 
under  this  name.  The  species  is  in  size  comparable  to 
Pelecyornis  tubulatus  with  which  it  agrees  closely. 

We  found  the  upper  four-fifths  of  a  tibio-tarsus,  associa- 
ted with  part  of  the  fibula,  the  sternum,  the  humerus,  and 
the  coracoid;  a  second  specimen  consisting  of  a  complete 
tarso-metatarsus,  and  fragments  of  the  pelvis,  vertebrae 
and  wing  bones;  a  third  specimen  consisting  of  part  of  the 
tibio-tarsus,  and  various  fragments;  a  fourth  consisting  of 
a  femur,  and  lastly  two  toes;  all  evidently  representing 
one  species,  which  in  most  respects  is  almost  identical  with 
Pelecyornis  tubulatus.  These  all  came  from  the  Chico  del 
Chubut,  west  of  Puerto  Visser. 


230  THE  DESEADO  FORMATION  OF  PATAGONIA 

The  humerus  has  a  large  head  but  is  considerably  flat- 
tened at  the  proximal  end.  The  internal  side  is  deeply 
excavated,  the  shaft  is  slender  and  light  as  though  the  wing 
were  quite  reduced,  though  not  so  much  as  in  Pelecyomis 
and  not  nearly  as  much  as  in  Phororhaciis. 

The  sternum  had  a  moderate  keel  but  both  this  and  body 
of  the  bone  are  very  thin,  so  much  so,  that  in  my  specimen, 
much  is  broken  away,  giving  the  figure  the  appearance  of 
the  bone  being  fenestrated,  which  wras  not  the  case.  In 
general  the  sternum  is  similar  to  Pelecyornis. 

The  coracoid  is  a  decidedly  stout  bone,  \vith  a  wide  dis- 
tal end  for  articulation  of  (he  sternum.  The  proximal  end 
has  a  long  articular  facet  for  the  scapula.  This  bone  is 
heavier  than  the  corresponding  one  in  Pelecyornis. 

The  femur  has  a  small  rounded  head  on  a  short  neck, 
the  articular  surface  spreading  over  the  entire  proximal 
end  of  the  bone.  Thus  the  trochanter  is  abbreviated  and 
does  not  rise  above  the  top  of  the  head.  The4  shaft  is  of 
considerable  length  and  fairly  heavy. 

The  tibio-tarsus  has  a  wide  flaring  end  to  receive  the 
articulation  of  the  femur.  The  bone  is  very  long  as  in 
Pelecyornis.  On  the  external  side  is  a  long  ridge  along 
which  the  fibula  was  attached  by  cartilage  or  by  ligaments, 
but  was  not  fused  to  the  tibio-tarsus.  The  shaft  is  appn  >\i- 
mately  cylindrical  in  section  and  fairly  heavy.  The  distal 
end  is  missing,  but  if  I  have  associated  correctly  the  speci- 
men figured  by  Ameghino,  the  condyles  are  ilattened,  the 
inner  being  the  flatter,  and  the  outer  rising  in  a  narrow 
margin. 

Figure  157  shows  a  fibula  which  would  have  occupied  the 
position  indicated  along  the  side  of  the  tibio-tarsus  and 
corresponds  entirely  with  the  same  bone  in  Pelecyornis. 

The  tarso-metatarstis  is  long  and  slender,  almost  exactly 
the  counterpart  of  the  same  bone  in  Pelecyornis.  The  bone 
has  a  triangular  upper  end,  with  (wo  shallow  articular 


LOXORNIS  CLIVUS 


231 


concavities,  separated  by  a  median  spine.  The  shaft  is 
rectangular  in  cross  section,  has  a  shallow  depression  on 
the  anterior  face  extending  from  the  upper  end  to  below 
the  middle  of  the  shaft;  while  on  the  posterior  surface  is  a 


Fig.    155.    Femur — 1/2 
natural  size. 


Fig.  157-  Fibula— 1/2 
natural  size;  outline 
from  impression  in  ma- 
trix. 


Fig.  156.  Tibio-tarsus 
— 1/2  natural  size;  fib- 
ula indicated  in  out- 
line. 


Fig.  158.  Tarso-met- 
atarsus,  front  view — 
1/2  natural  size. 


similar  furrow,  which  is  however  bounded  by  a  higher 
ridge  on  the  external  margin.  The  distal  articular  condyles 
are  almost  bilaterally  symmetrical,  the  middle  one  being 
about  half  again  as  large  as  the  two  lateral  ones.  Just 
above  the  cleft  between  the  condyles  for  digits  III  and 
IV  there  is  a  moderate  sized  perforation. 


THE  DESEADO  FORMATION  OF  PATAGONIA 


Of  the  phalanges,  I  have  two  unguals  which  are  narrow 
curved  claws.  These  were  not  found  in  association  with 
any  of  the  foregoing  bones,  but  correspond  in  size  and 
general  character  to  those  of  Pelecyornis,  and  so  I  consider 
them  as  belonging  to  this  genus  and  species. 


Fig.   159-    Ungual   pha- 
lanx— 1/2  natural   size. 


Fig.  1 60.  Femur  of 
unknown  bird — natural 
size;  special  No.  3217. 


Ameghino  has  suggested  that  the  genus  was  related  to 
ducks,  but  with  the  more  complete  material  it  seems,  in 
general  build,  much  closer  to  the  aberrant  land  birds  of  the 
Tertiary  of  South  America,  Pelecyornis  and  Phororhacus; 
and  I  am  not  in  position  to  say  what  their  derivation  may 
have  been. 

Beside  the  above  species  there  are  several  more  or  less 
complete  but  isolated  bones  indicating  the  presence  of  other 
and  much  smaller  birds.  I  figure  such  a  femur  natural  size. 


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